After the operation on Gus's leg, the group is playing cards. The sound is the same audio from the card game earlier in the film. Ritt stays. Kovac takes three cards. You can see when Kovac supposedly says, "Three cards," his lips don't move at all.
The fish bait is a large Cartier multi-link diamond bracelet. It is used unfastened, so hangs straight down when hooked to the fishing line. However, when underwater it is shown as a small, plain, ring.
After Connie helps the first man onto the lifeboat, she is holding the camera with her right hand and helping him with her left hand. In the subsequent shoot, she is no longer holding the camera and her right is wet and dirty.
In the beginning of the film, a German U-boat crew member is floating in the water. He is wearing a life jacket with the words "Deutsches Reich U 78" printed on it. If they decided to print words on the jacket, Kriegsmarine" would be more appropriate. Also the U-78 was used as a trainer and never saw combat.
When Connie offers to use her diamond bracelet as a fishing lure, the fish that swallows it is a carp, a fresh water fish, which would be unlikely to strike at a flashy lure anyway since it is a toothless herbivore.
The goof item below may give away important plot points.
A stuntman, portraying Gus, is briefly seen standing in the stern of the boat before a wave throws him overboard, although Gus just had his leg amputated moments before and he was lying down! You can see that the stuntman actually jumps into the water before the wave hits. The "amputated" leg can also be seen tied behind Gus's thigh when they get him back to the boat.