Corrected entry: When the seaplane leaves San Francisco it flies west over the complete Golden Gate bridge. The movie is set in 1936, the Golden Gate bridge wasn't completed until 1937.
Corrected entry: After Indiana Jones has run the staff car containing Belloq, Toht, et al, off the road to Cairo with the truck, look at the driver of the staff car- he immediately anticipates Paul Freeman (Belloq) striking him two seconds before Freeman actually does by covering his head to protect himself from Freeman's hit.
Corrected entry: U-boats were more than four times as fast on the surface (running on diesel engines) than when submerged (running on batteries). Since Germany was not at war at this time they would have run the boat on the surface almost exclusively. Since the boats were so hard for other surface vessels to see, the Captain would have maintained a constant look out on deck. There is no way Indy could have stayed hidden for the entire voyage.
Corrected entry: When Indiana and the other guy are removing the stone cover where the Ark is kept, they are struggling, yet they can lift the Ark out with relative ease. The Ark is made of solid gold and the lid itself is said to need two men to lift, plus it should contain the two stone tablets with the ten commandments on. It should have weighed just as much if not more than the stone covering.