Continuity mistake: After Mr. Palmer walks over and tries to pick up Claude Mulvihill's gun (which Jack kicks away) we see Jack's hat on his left. In the next shot as Jake picks it up it's now on his right. (01:19:40)
Continuity mistake: When Poirot and Mr. Ratchett first meet in the restaurant car, Poirot has to correct Ratchett's pronunciation of his name. Poirot then points with his right hand toward Ratchett, but when it cuts to a close-up of Poirot, both his hands are on the table. The angle changes back, and Poirot's hand is once again lifted.
Continuity mistake: The guests are discussing how they were lured in by Mr. Owen. Aznavour pitches in with his drunken comments occasionally, but his arm/hand position is often wrong. For instance when the doctor mentions his reason, Aznavour's left arm is the only one above the music sheet, but in the close-up he's holding the glass with both hands, over the sheet. (00:20:55)
Continuity mistake: Gene Hackman returns a second cookie to Harrison Ford's dish that he hadn't taken - or perhaps it's the same cookie he picked up and returned a moment earlier. Either way, the cookie had suddenly appeared in Hackman's hands going from one shot to another. (00:30:35)