Factual error: In the ship yard after the party, one of the navy crew is working on a sub and he is using a yellow plastic handled grinder. All tools in this era were metal handled. He's also wearing tennis shoes. (00:13:15)
Continuity mistake: In the start of the film Matthew McConaughey is sitting on a porch at a wedding reception smoking a cigar, in one shot he has a stub left then in the next it's a new one. (00:12:20)
Continuity mistake: During the first mission briefing, the commander is pointing to the map and you can clearly see the top secret photos of the enigma sitting by the manila envelope, but right after that shot he pulls the photos out of the envelope and hands them to people. (00:24:20)
Continuity mistake: During the mission briefing, the position of the Top Secret folder changes from the centre of the map to the side of the map between instant cuts. (00:23:30)
Continuity mistake: Tyler states he doesn't know what's going on to a few seamen and tells them to do their jobs. As the shot changes the seamen have all disappeared from the background. (00:14:50)
Continuity mistake: Just after unveiling the Nazi plates on the SS-33, there are 3 seamen wearing brown jackets next to the deck gun. When the shot changes there are 4. (00:25:00)
Continuity mistake: When Tyler is out on the deck, he has his hand raised. When the "boat secure" order is shouted it's now lowered and holding on to his glass. (00:12:10)
Answer: The scars you see on Tank's face are fake, pure makeup. They wanted the character to have a gritty look.