diff --git a/lisp/ob-core.el b/lisp/ob-core.el
index 9ac998dab..1a6bb8452 100644
--- a/lisp/ob-core.el
+++ b/lisp/ob-core.el
@@ -2972,7 +2972,7 @@ If the table is trivial, then return it as a scalar."
 (defun org-babel-string-read (cell)
   "Strip nested \"s from around strings."
   (org-babel-read (or (and (stringp cell)
-                           (string-match "\\\"\\(.+\\)\\\"" cell)
+                           (string-match "\"\\(.+\\)\"" cell)
                            (match-string 1 cell))
                       cell) t))
 
diff --git a/lisp/org-agenda.el b/lisp/org-agenda.el
index 069abbecb..31f3dace2 100644
--- a/lisp/org-agenda.el
+++ b/lisp/org-agenda.el
@@ -9480,7 +9480,7 @@ the resulting entry will not be shown.  When TEXT is empty, switch to
     (goto-char (point-min))
     (cl-case type
      (anniversary
-      (or (re-search-forward "^*[ \t]+Anniversaries" nil t)
+      (or (re-search-forward "^\\*[ \t]+Anniversaries" nil t)
 	  (progn
 	    (or (org-at-heading-p t)
 		(progn
diff --git a/lisp/org-element.el b/lisp/org-element.el
index 0fea9b38a..e4e704d0d 100644
--- a/lisp/org-element.el
+++ b/lisp/org-element.el
@@ -2150,7 +2150,7 @@ containing `:key', `:value', `:begin', `:end', `:post-blank' and
     ;; this corner case.
     (let ((begin (or (car affiliated) (point)))
 	  (post-affiliated (point))
-	  (key (progn (looking-at "[ \t]*#\\+\\(\\S-+*\\):")
+	  (key (progn (looking-at "[ \t]*#\\+\\(\\S-*\\):")
 		      (upcase (match-string-no-properties 1))))
 	  (value (org-trim (buffer-substring-no-properties
 			    (match-end 0) (point-at-eol))))
diff --git a/lisp/org-list.el b/lisp/org-list.el
index 727ec6747..cfd674f85 100644
--- a/lisp/org-list.el
+++ b/lisp/org-list.el
@@ -2657,7 +2657,7 @@ Return t if successful."
 		(error "Cannot outdent beyond margin")
 	      ;; Change bullet if necessary.
 	      (when (and (= (+ top-ind offset) 0)
-			 (string-match "*"
+			 (string-match "\\*"
 				       (org-list-get-bullet beg struct)))
 		(org-list-set-bullet beg struct
 				     (org-list-bullet-string "-")))
diff --git a/lisp/org-mhe.el b/lisp/org-mhe.el
index 969bff3cc..a37c41ad0 100644
--- a/lisp/org-mhe.el
+++ b/lisp/org-mhe.el
@@ -142,7 +142,7 @@ So if you use sequences, it will now work."
   "Return the name of the message folder in an index folder buffer."
   (save-excursion
     (mh-index-previous-folder)
-    (if (re-search-forward "^\\(+.*\\)$" nil t)
+    (if (re-search-forward "^\\(\\+.*\\)$" nil t)
 	(message "%s" (match-string 1)))))
 
 (defun org-mhe-get-message-folder ()
diff --git a/lisp/org-mobile.el b/lisp/org-mobile.el
index 7d2640a5f..baac7a992 100644
--- a/lisp/org-mobile.el
+++ b/lisp/org-mobile.el
@@ -859,11 +859,11 @@ If BEG and END are given, only do this in that region."
 	    (cl-incf cnt-error)
 	    (throw 'next t))
 	  (move-marker bos-marker (point))
-	  (if (re-search-forward "^** Old value[ \t]*$" eos t)
+	  (if (re-search-forward "^\\** Old value[ \t]*$" eos t)
 	      (setq old (buffer-substring
 			 (1+ (match-end 0))
 			 (progn (outline-next-heading) (point)))))
-	  (if (re-search-forward "^** New value[ \t]*$" eos t)
+	  (if (re-search-forward "^\\** New value[ \t]*$" eos t)
 	      (setq new (buffer-substring
 			 (1+ (match-end 0))
 			 (progn (outline-next-heading)
diff --git a/lisp/org-mouse.el b/lisp/org-mouse.el
index 0cca65c8d..13d88dad7 100644
--- a/lisp/org-mouse.el
+++ b/lisp/org-mouse.el
@@ -633,7 +633,7 @@ This means, between the beginning of line and the point."
 	 ,@(org-mouse-list-options-menu (mapcar 'car org-startup-options)
 					'org-mode-restart))))
      ((or (eolp)
-	  (and (looking-at "\\(  \\|\t\\)\\(+:[0-9a-zA-Z_:]+\\)?\\(  \\|\t\\)+$")
+	  (and (looking-at "\\(  \\|\t\\)\\(\\+:[0-9a-zA-Z_:]+\\)?\\(  \\|\t\\)+$")
 	       (looking-back "  \\|\t" (- (point) 2)
 			     (line-beginning-position))))
       (org-mouse-popup-global-menu))
diff --git a/lisp/org-plot.el b/lisp/org-plot.el
index aa34e4011..a5635e326 100644
--- a/lisp/org-plot.el
+++ b/lisp/org-plot.el
@@ -336,7 +336,7 @@ line directly before or after the table."
                    (insert "\n")
                    (insert-file-contents (plist-get params :script))
                    (goto-char (point-min))
-                   (while (re-search-forward "$datafile" nil t)
+                   (while (re-search-forward "\\$datafile" nil t)
                      (replace-match data-file nil nil)))
 	  (insert (org-plot/gnuplot-script data-file num-cols params)))
 	;; Graph table.
diff --git a/lisp/org-protocol.el b/lisp/org-protocol.el
index d9fdef00e..0577c3151 100644
--- a/lisp/org-protocol.el
+++ b/lisp/org-protocol.el
@@ -330,7 +330,7 @@ returned list."
 	 (len 0)
 	 dir
 	 ret)
-    (when (string-match "^\\(.*\\)\\(org-protocol:/+[a-zA-z0-9][-_a-zA-z0-9]*:/+\\)\\(.*\\)" trigger)
+    (when (string-match "^\\(.*\\)\\(org-protocol:/+[a-zA-Z0-9][-_a-zA-Z0-9]*:/+\\)\\(.*\\)" trigger)
       (setq dir (match-string 1 trigger))
       (setq len (length dir))
       (setcar l (concat dir (match-string 3 trigger))))
diff --git a/lisp/org-table.el b/lisp/org-table.el
index f4e3d35a2..e22ee9503 100644
--- a/lisp/org-table.el
+++ b/lisp/org-table.el
@@ -1156,7 +1156,7 @@ to a number.  In the case of a timestamp, increment by days."
 			      (- (org-time-string-to-absolute txt)
 				 (org-time-string-to-absolute txt-up)))
 			     ((string-match org-ts-regexp3 txt) 1)
-			     ((string-match "\\([-+]\\)?\\(?:[0-9]+\\)?\\(?:\.[0-9]+\\)?" txt-up)
+			     ((string-match "\\([-+]\\)?[0-9]*\\(?:\\.[0-9]+\\)?" txt-up)
 			      (- (string-to-number txt)
 				 (string-to-number (match-string 0 txt-up))))
 			     (t 1)))
@@ -2327,7 +2327,7 @@ LOCATION instead."
 	      "\n"))))
 
 (defsubst org-table-formula-make-cmp-string (a)
-  (when (string-match "\\`$[<>]" a)
+  (when (string-match "\\`\\$[<>]" a)
     (let ((arrow (string-to-char (substring a 1))))
       ;; Fake a high number to make sure this is sorted at the end.
       (setq a (org-table-formula-handle-first/last-rc a))
@@ -2375,7 +2375,7 @@ LOCATION is a buffer position, consider the formulas there."
 		       (cond
 			((not (match-end 2)) m)
 			;; Is it a column reference?
-			((string-match-p "\\`$\\([0-9]+\\|[<>]+\\)\\'" m) m)
+			((string-match-p "\\`\\$\\([0-9]+\\|[<>]+\\)\\'" m) m)
 			;; Since named columns are not possible in
 			;; LHS, assume this is a named field.
 			(t (match-string 2 string)))))
@@ -3236,7 +3236,7 @@ known that the table will be realigned a little later anyway."
 		    (cond
 		     ((string-match "\\`@-?I+" old-lhs)
 		      (user-error "Can't assign to hline relative reference"))
-		     ((string-match "\\`$[<>]" old-lhs)
+		     ((string-match "\\`\\$[<>]" old-lhs)
 		      (let ((new (org-table-formula-handle-first/last-rc
 				  old-lhs)))
 			(when (assoc new eqlist)
@@ -3659,7 +3659,8 @@ Parameters get priority."
       (setq startline (org-current-line))
       (dolist (entry eql)
 	(let* ((type (cond
-		      ((string-match "\\`$\\([0-9]+\\|[<>]+\\)\\'" (car entry))
+		      ((string-match "\\`\\$\\([0-9]+\\|[<>]+\\)\\'"
+				     (car entry))
 		       'column)
 		      ((equal (string-to-char (car entry)) ?@) 'field)
 		      (t 'named)))
diff --git a/lisp/org.el b/lisp/org.el
index ca4c5d581..d5a7bf526 100644
--- a/lisp/org.el
+++ b/lisp/org.el
@@ -10058,7 +10058,7 @@ This is still an experimental function, your mileage may vary."
    ((and (equal type "lisp") (string-match "^/" path))
     ;; Planner has a slash, we do not.
     (setq type "elisp" path (substring path 1)))
-   ((string-match "^//\\(.?*\\)/\\(<.*>\\)$" path)
+   ((string-match "^//\\(.*\\)/\\(<.*>\\)$" path)
     ;; A typical message link.  Planner has the id after the final slash,
     ;; we separate it with a hash mark
     (setq path (concat (match-string 1 path) "#"
@@ -21994,7 +21994,7 @@ assumed to be significant there."
   (save-excursion
     (skip-chars-backward "[ \t]")
     (skip-chars-backward "\\\\")
-    (looking-at "\\\\\\\\\\($\\|[^\\\\]\\)")))
+    (looking-at "\\\\\\\\\\($\\|[^\\]\\)")))
 
 (defun org-fill-paragraph-with-timestamp-nobreak-p ()
   "Non-nil when a new line at point would split a timestamp."
diff --git a/lisp/ox-ascii.el b/lisp/ox-ascii.el
index 25317cb8a..7917e3dad 100644
--- a/lisp/ox-ascii.el
+++ b/lisp/ox-ascii.el
@@ -1472,8 +1472,8 @@ contextual information."
 		   (replace-regexp-in-string
 		    "-" "•"
 		    (replace-regexp-in-string
-		     "+" "⁃"
-		     (replace-regexp-in-string "*" "‣" bul))))))))
+		     "\\+" "⁃"
+		     (replace-regexp-in-string "\\*" "‣" bul))))))))
 	 (indentation (if (eq list-type 'descriptive) org-ascii-quote-margin
 			(string-width bullet))))
     (concat
diff --git a/lisp/ox-latex.el b/lisp/ox-latex.el
index e09312f65..a147111ed 100644
--- a/lisp/ox-latex.el
+++ b/lisp/ox-latex.el
@@ -1610,7 +1610,7 @@ INFO is a plist used as a communication channel."
 
 (defun org-latex-clean-invalid-line-breaks (data _backend _info)
   (replace-regexp-in-string
-   "\\(\\end{[A-Za-z0-9*]+}\\|^\\)[ \t]*\\\\\\\\[ \t]*$" "\\1"
+   "\\(\\\\end{[A-Za-z0-9*]+}\\|^\\)[ \t]*\\\\\\\\[ \t]*$" "\\1"
    data))
 
 
diff --git a/lisp/ox.el b/lisp/ox.el
index 73eec2fca..054e10fb7 100644
--- a/lisp/ox.el
+++ b/lisp/ox.el
@@ -3300,7 +3300,7 @@ storing and resolving footnotes.  It is created automatically."
 			   (setq value (replace-match "" nil nil value)))))
 		   (lines
 		    (and (string-match
-			  ":lines +\"\\(\\(?:[0-9]+\\)?-\\(?:[0-9]+\\)?\\)\""
+			  ":lines +\"\\([0-9]*-[0-9]*\\)\""
 			  value)
 			 (prog1 (match-string 1 value)
 			   (setq value (replace-match "" nil nil value)))))