Factual error: While handling the ignition coil cable to the distributor cap, Joe Pesci tells De Niro that the timing chain needs adjustment in his truck. A truck of that year with an inline Chevy motor would not have a timing chain at all, instead this truck would be equipped with a direct drive timing gear. Even if it had a timing chain, it would be behind the water pump and a cover. It would have been a several hour job to replace, not possible to adjust it.
Revealing mistake: How on Earth can Selby get those skin tight T-shirts over that huge cast on her arm? They cannot possibly stretch any more than they already are - look at the scene where she and Eileen are checking the mail. There is no way that sleeve would fit over the cast without ripping! It is well beyond the capacity of that tight T-shirt to stretch to that extent! Obviously Christina Ricci had the cast fitted after she was in costume.
Factual error: After the successful Trinity test in 1945, people in a crowd are holding small US flags with 50 stars on them (offset rows). At the time there were only 48 states and the flag had 48 stars in even rows. The 50 star flag didn't exist until 1960, after Alaska and Hawaii were made states in 1959.
Factual error: The interior shots of the Gemini and Apollo Spacecraft show worn and dirty panels, knobs, switches and circuit breakers. The movie most likely used some original cockpit trainers, but in reality the astronauts were flying brand new spacecraft that were spotless.
Visible crew/equipment: At the beginning of the film when being rescued from the quicksand you can see someone's legs and hand behind the horse, holding it. (00:10:00 - 00:11:00)
Visible crew/equipment: During the "full attack" at the start of the Battle of Stirling Bridge, Wallace repeatedly shouts, "Hold," and in the wideshot right before Wallace finally shouts, "Now!" as the horses gallop towards the right side of the screen, we can see a white car at the left side of the screen. Viewed widescreen version. (01:27:15)
Plot hole: Searching for the source of the river, the raft is going downstream. Return trip it's also downstream. Generally, no matter where they are going, the rafts keep floating downstream.
Continuity mistake: When the main character goes to visit his friend that had been shot in Iraq, they're driving down a country road in a 2 door Dodge Challenger, but when inside the vehicle it's a Dodge Charger, which is a four door car.
Factual error: In a scene in 1980, Brian May is teaching everyone the beat for his new song "We Will Rock You." However that song was released in 1977.
Factual error: Robert McNamara is wearing a multi colored Polo shirt talking to Mrs. Graham in 1971. The Ralph Lauren Company did not make the shirts until 1972.
Factual error: When Mark types email addresses in to tell people about facemash, he writes to several people @harvard.edu. At the time the movie takes place, undergraduate email addresses were all of the form firstname.lastname@example.org. Furthermore, the network brought down by facemash would have been referred to as the FAS network. (FAS stands for Faculty of Arts and Sciences; the eponymous network covered all buildings within the College and Graduate School of Arts and Sciences.).
Factual error: In the scene where the Navy Seals are riding in the cars, the VA state vehicle inspection can be read from behind. It read "6 13" for June 2013. This would have been correct for the period the film was made, but not for the time of the incident.
Visible crew/equipment: While Barnum and Phillip sing "The Other Side" Phillip uses two stools to get up and down from the bar top. When he steps down from the bar top, in this wideshot (also the first shot of them in the pub and other shots) the two upright stools Phillip used are secured with additional support, note the floor area underneath the stools' legs have the same pattern as the rest of the floor, though we can see the outline where the pattern's lines don't match up. Additionally, we also see three actors' marks (in the shape of an "L") on the floor in front of the bar, which will be where Barnum and Phillip will stand when they agree on the ten percent. (00:36:05)