Factual error: In the early part of the movie, there is a shot of the outside of Triple O's bar. The scene takes place in 1975 and "Coors" is advertised on the outside of the bar. Coors beer was not available in Boston/East Coast in 1975. It was only available from the 1980's.
Factual error: In the 1998 part of the movie, before the launch of the iMac, Steve is wearing his trademark black turtleneck and jeans for the presentation. At the actual launch in 1998, Steve wore a suit.
Factual error: The delivery van bringing gear for the walk has a 718 area code on it. That area code did not exist until 1984.
Other mistake: When Otto Preminger calls Trumbo from his car to announce that Trumbo's real name would be credited for Exodus, Preminger tells him to look at the front page of the New York Times. The problem is that Trumbo has already picked up the paper from his counter and is reading before Preminger even tells him which newspaper features the article.