Continuity mistake: Arnie enters the parking lot driving on two wheels crying "Woooa." The close shots show him with one hand on the wheel and the other outside on the window; but on the wide shots, with the stunt, both hands are inside and his mouth closed but still the cry is heard. This mistake goes on every time angle changes.
Revealing mistake: When Jemma enters the headshrinker's laboratory, there is a table with three heads on it each encased in glass. When it goes in close-up on the middle head, you can see that the table has a hole where the actor can slip in his head.
Continuity mistake: Inside Lord Peel's study, Poirot asks Lady Westholme what did she do after lunch, since "You did not immediately go for your walk, I believe." Peter Ustinov poses the question with his hands behind his back, but Lauren Bacall's answer answers with the stand-in for Ustinov posing with his hand on his hip. (00:54:40)
Continuity mistake: The ruler in Tess' hands instantly changes design. It looks like she flipped it over between shots, but without any time or reason to do so. (00:19:20)
Continuity mistake: The 3 girls lock Sadie Shelton in a closet and then bring a chair to secure the door and Rose sits. A couple of seconds later, Rose is standing again holding the door. (01:28:05)
Continuity mistake: When Bill Pullman is poisoned he has a defined red cross painted on his forehead. He stumbles around for a while and the cross smears to the point where it looks like a big red blob. But when he finally dies and looks at the camera, the cross isn't smeared at all. (01:16:35)
Continuity mistake: Throughout the film Elvira wears her trademark black dress, split to the top of her thigh, and underneath it she always wears black pantyhose. Inexplicably, this changes to black stockings and suspenders when she is undressing for bed on her first night in her new house. (00:31:35)
Continuity mistake: In the scene where Bill's old boss comes back to see him notice when Bill shoots him and takes the drink. All of the drink comes out of his chest because of the bullet holes. Well notice his shirt is all wet, then in the next scene when he takes off his hat his chest is all dry.
Revealing mistake: During the fight montage, the winner of the first match wins by kicking his opponent in the face. His foot never makes contact.
Visible crew/equipment: When Jamie Lee Curtis is leaving John Cleese's office, she kisses him goodbye and calls him Uncle. After she has left, you can clearly see the cameraman move into view of the mirror. (00:33:27)
Continuity mistake: When Michelle tries to reach for the statue, in the close-up there's a dim light shining and a small souvenir license plate next to it. Also, there's a white bag to the left of the shoe. In the wide angle, the light is brighter, the license plate is gone, and the white bag is now to the right of the shoe.