Factual error: Maverick and the rest of the poker players throughout the movie are using plastic poker chips. You can tell by the sound they make when thrown. Poker chips during that time were made out of wood or ceramic.
Factual error: When Maverick is talking to Joseph in his native language telling him to act angry, if you look just above Joseph you will see a jet flying above his head in the distance. (01:02:10)
Factual error: When the camera focuses in the the clock striking five, we see the clock has patent number "19701". While this patent does apply to a clock, it was not issued until 1900, 25 years after the movie was set.