Other mistake: The security monitor in Valentin's office shows a cinematic wide shot of the casino with the camera moving. It seems unlikely that a CCTV camera would be mounted to a crane to perform elegant moves like this. (00:43:55)
Other mistake: When he is talking to his sister in-law during work on the phone, the red wire, which was connecting them so they could talk, dropped or fell out of place. Even though this happened, the conversation still continued.
Other mistake: Both Brenner and Sunhill are First Sergeants, yet their military IDs are very different: Brenner's is just a plastic ID card, but Sunhill has both a police ID badge as well as a paper card authorizing her to make arrests.
Suggested correction: Paul Brenner is a Chief Warrant Officer 4, Sarah Sunhill is a Chief Warrant Officer 2. His mil ID is 1SG because he is undercover, it's not Paul Brenner's. First Sergeants are never CID agents, though Master Sergeants could be. Brenner holds his CID credentials to the MP's at the gate when heading to the murder scene.
Other mistake: When Porter cuts the fuel line on the car and is about to light it, Carter's henchmen see him and act surprised. Despite having ample time to get out (as any rational person might do), they just sit in the car and wait for it to explode.
Other mistake: Tom Ripley's ticket says first class in the limo, but when he boards, the rich girl says she saw his stuff in the third class stack. Dickie also says that he's a third class mooch, but according to his ticket he rode first class, so that'd make him a first class mooch, not third. His cabin is never shown. (00:07:20)
Other mistake: At the very end, Alec Baldwin drives away and other cars follow him. Problem is: two cars after Alec's car, the green traffic light turns orange, then red, and the cars keep coming. In all, 6 cars go through the red light.