Continuity mistake: When Stanley is in jail, he put toilet papers on the toilet seat. But a few seconds later the toilet paper is not on the toilet. (01:10:35 - 01:13:10)
Continuity mistake: When Dorian arrives at the Coco Bongo Club at the end of the movie, he smashes the doors which end up on the floor, but when the fight is over and everybody is leaving the club, the doors are back on the doorframe. (01:17:20 - 01:28:05)
Continuity mistake: When Stanley is doing the Cuban dance watch his legs. Whenever the camera is behind him you can see him wearing black kneepads but when the camera is in front they aren't there. (00:58:20)
Continuity mistake: After Stanley found the mask and gets back home and is watching some cartoons, Milo wants him to throw the frisbee. When the camera is switching from Stanley to Milo and then back to Stanley again you'll see the remote move to the right. (00:15:45)
Continuity mistake: In the bar scene at the end of the movie Stanley dives over the bar while Dorian's thugs shoot at him, when they stop shooting you see one of the thugs drop the magazine out of the gun then the scene cuts away from him and when it cuts back you see the thug drop the magazine out of the gun again. (01:25:20)
Continuity mistake: When Dorian dismisses his charges to capture the Mask for 50,000.00, Tina and Dorian chat. She is about to light her cigarette but doesn't. In the next cut away there is smoke in the air but she still hasn't lit it yet. As the scene continues you only see smoke when Diaz has her back to the camera.
Continuity mistake: When Tina kicks the mask out of Dorian's hand and Milo leaps through the air to catch it, he catches it with his mouth at the mask's chin, yet when he lands the mask has been turned round so the chin end is now facing the ground. (01:22:45)
Continuity mistake: When the Mask crashes Nico's party at the Coco Bongo, Nico shoots him. According to the sounds, the gun should have flashed 8 times but it only flashes 2 times. (01:18:25)
Continuity mistake: When Stanley Ipkiss first appears as the Mask, after having jumped through the end of hall apartment window with Mrs. Peenman shooting at him, he is approached by several thugs, one of which asks him the time. The thugs begin chasing him down the alley. The thug with the beard and baseball cap at the beginning of this chase is shirtless. Halfway through the chase he now has a flannel shirt on which is unbuttoned, (visible when he jumps over a barrel as it flies open). As he stops, now the flannel shirt is buttoned up to the very top button. The entire chase scene is 4-5 seconds long. (00:19:45)
Continuity mistake: When Stanley is trying to get in the club, Dorian tells the bouncer to "lose him". The line is immediately repeated due to an editing screw up. (00:10:51)
Continuity mistake: In the very beginning, when the scuba diver is trying to open the chest and gets hit with the pipe, at first the pipe is held by a rope near the middle and when it's lowered into the water it is held by a chain at each end. After it hits the guy and is let go from the chains they are wrapped around three times. (00:01:00)
Continuity mistake: The "loaner" car Stanley picks up at the mechanics is a 1951 Studebaker Champion. However, the car that falls apart on the bridge is a 1950 Studebaker Commander.
Continuity mistake: When Dorian puts on the mask for the first time, right before all the smoke starts reducing, pay close attention to his goons. Some of them change position. (Clearly those were two takes pasted together, one with Dorian without the mask, and one with.) (01:04:25)
Continuity mistake: When The Mask first visits the Coco Bongo and dances wildly with Tina, they perform a series of impressive manouvers and The Mask then dips Tina and holds her in that position. At this moment, Tina is revealed to be a stunt double, not Cameron Diaz, just before the camera zooms into a close up of Jim Carrey.