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.
Audio problem: When Tina is tied to the palm tree with the bomb armed and Ipkiss is fighting with the goons. Ipkiss fights with Dorian and punches him over and over with Dorain on his back. The punching sounds are VERY obviously off from the action.
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.
Revealing mistake: When the super-stretch limo is pulling up to the club, we see window after window go by, then the picture cuts for a moment to the crowd watching. Upon returning to the limo shot, the edge of the front door can be seen on the left side of the screen, ruining the illusion of the ridiculously long limo.
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.
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.
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 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.
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.
Factual error: In the first scene of the movie, a diver is underwater, and he is talking to someone on the radio. How can he talk, when he is biting down on the mouthpiece from his scuba tanks? And his mouth is obviously not moving.
Continuity mistake: During the musical number "Cuban Pete", Jim Carrey's blue shirt is sometimes tucked in and sometimes is not.
Continuity mistake: When The Mask paints the flush handle, near the end of the movie, watch the far left hand side when it shows Tina and The Mask. The Mask is shutting a door on the tree where the flush handle really is.
Revealing mistake: When The Mask is dancing with Tina and he turns her into a human tornado while spinning her around, none of the onlookers in the crowd show the slightest bit of amazement at the impossible feat that just occurred in front of them, indicating that the extras were not directed to react to the special effects.
Visible crew/equipment: Towards the end of the film you see the long haired baddie grab Milo by the hind legs (just before Milo puts the mask on). As Milo starts to change you can just about see the baddie who is holding his legs, except he is now a different person with brown curly hair, nobody who is seen prior or following this shot. Presumably he is the dog trainer.
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.
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.
Continuity mistake: When Dorian, as The Mask, breaks down the doors of the Coco Bongo, you see the door topple onto the doorman on the left. When the camera cuts back, he is on top of the door.
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.
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.
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.
Continuity mistake: When Cameron Diaz goes to the jail and meet Stanley they almost kiss for the first time. She is wearing bright red lipstick. A few minutes later she is running down an alley outside of the prison from her boyfriend. She is wearing soft pink lipstick.
Audio problem: In the scene where Milo jumps at the cell window to save Ipkiss, Stanley says "good boy," but his mouth doesn't move.
Continuity mistake: While in Mrs. Peenmans' hall, just before she shoots him, his hands switch places on the mallet. In the first shot, his left hand is on the bottom, right hand is on the top. In the other two shots, it is vice-versa.
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.
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.)
Continuity mistake: When Dorian's boss shoots him in the stomach it switches from the boss to Dorian several times. Each time Dorian's buttons change colours from black buttons to white buttons to no buttons.
Continuity mistake: When Ipkiss is in jail and he is summoning Milo, the dog jumps up through the bars. When Ipkiss pulls him through, one of the bars swings a little bit. It must not have been a very secure cell.