Plot hole: Radl and Steiner discuss the entire scheme to kidnap Churchill on the Alderney docks - in full view and hearing of a number of civilians (who shouldn't be there, pace another posting), including local fishermen. Though the Germans banned all fishing activities in the Channel islands including Alderney in 1941, they were well aware that there was a flow of information from the island to military authorities in the mainland. Why would they be so stupid as to discuss a top secret military mission in public? In reality, they wouldn't even discuss it in front of their own men.
Plot hole: Captain Smolsky only gets hit in the back with the plaster. So why, later on, is his entire body covered in hardened plaster, like a mummy?
Plot hole: In the runaway train scene, Gene Wilder uncouples the train from the forward car, and has to make a dramatic leap to get back to the uncoupled car. Is there any reason he couldn't have uncoupled the train from the back car and just stayed put? It seems an unnecessary bit of drama.
Plot hole: When the Ferrari stops for fuel at night, Franco decides to spend the night with the girl in the Mercedes. His partner protests, then abandons Franco to continue the race. The next morning, the girl drives Franco to meet up with the Ferrari again. This is a coast-to-coast race, planned out in detail by each crew long before to take the shortest course at the highest speeds possible. First car to L.A. wins. It isn't possible for the Mercedes to just 'catch up' to the Ferrari the next morning unless the Ferrari was taking a wildly wandering course or driving incredibly slow for hours.
Plot hole: When Josey gives the redlegs a "Missouri boat ride" by shooting the tow rope on the ferry, the craft drifts off down stream, silhouetted in the setting sun. The problem is, Josey and the kid are on the east bank, instead of the west bank where the Indian nation is located.
Plot hole: In the final scene where they all leave along the passage; the father rolled out on a stretcher and the others casually walking out, you can tell by their smooth passage along the corridor that all the dead bodies have been removed, but this would have taken at least half an hour if not longer, so it would make no sense in reality for them all to wait for all the bodies to be removed before they left as they would have been the first to leave due to the traumatic experience they had just been through.
Plot hole: Funn, Eggs, and Bell, accompanied by Vilma, enter the theater, ready to show their finished Silent Movie project to the audience. However, only a night previous, Funn, inebriated, is rescued from the gutter, by his friends. A scene immediately following, shows them 'reviving' him with coffee. When did they find ample time to shoot their film? The time frame doesn't add up.
Plot hole: Since the criminals who used the dogs to rob the bank in the first movie were never apprehended (No criminal worth their salt would tell the authorities their caper was spoiled because the canines ran off with their loot), there is no way the people who are hunting the dobermans in the beginning of this movie would know the dogs were still carrying the cash. (00:18:00)
Plot hole: For the murder on the highway to happen, the killer (who is not a mastermind, but someone who has a daily job and who never killed before) had to sabotage the car of the victim in such a clever way that he'd stop at a specific point and time (so, predicting also he'd escape out of town and do it through a certain route, which he had no way to predict), and that he'd react to the mechanical problem waving at passing cars walking in the middle (literally in the middle, not the side, or the emergency lane; perfectly in the middle of it) of a highway, where he can drive his semi into him - all while the fog is incredibly thick. Needless to say, it is all a bit too convenient.