Factual error: Halfway into the film, a scene shows Capote talking on a beige telephone. The receiver is a modular (plug in) type. Modular phones were not introduced until after 1966. The time frame for this movie is 1959 through 1963. All other scenes in this movie show the correct type of receiver (wired, not plug-in).
Factual error: In the scene prior to the Braddock/Baer fight, when Jim's wife Mae comes into the locker room and gives him the heartfelt spiel about being behind him in this fight after all, she leaves the room and as she leaves Jim, Russell Crowe, is standing there in a white "wife beater" tank top. It is a new one with a screened on tag by either Fruit of the Loom or Hanes. Screened-on tag tees didn't come about until the last few years.
Factual error: Towards the beginning of the film, the Cashes receive a notice about their rent. It's the 1950's and the address has a ZIP code. ZIP codes were not introduced until 1963.
Factual error: In the movie, Marcus is out of high school, probably in his late teens, early 20's. Going by 50 cent's age, this would probably put the movie back in the mid 90's. When he flashes back, he's younger, put it in the late 80's. Well, in one sequence when he's young, he's playing with friends and has on red and white low Air Jordan 2's on. These were not made in this color until 2004. Same in another sequence when he's talking to Majestic while eating fast food, he's wearing some white and green Air Jordan 4's, which also didn't come out til 2004, which in fact is when the movie was filmed.
Factual error: The song "I Won't Dance" was not written until the early-'30s, at least six years after the time it was shown being used in the film. However, it is still performed in the dining room scene.
Factual error: In the scene where Brian gets fired from The Rolling Stones, Keith Richards sees a live album Jimi Hendrix and mentions it, Brian says Hendrix sent him one. But this scene must have taken place in 1969: Hendrix hadn't released any live albums earlier than 1970.