Best biography movie mistakes of 1991
Factual error: Warren Beatty refers to the "Hoover Dam" being able to generate the power needed for Las Vegas and his Flamingo casino. The problem is that he supposedly made the comment in 1937. At that time, the "Hoover Dam" was still called "Boulder Dam." It wasn't renamed to honour President Herbert Hoover until about ten years later.
Factual error: Hawking explains how time slows as one approaches a black hole's event horizon. To illustrate this a CGI-animated analog wristwatch is shown ticking away the seconds progressively more slowly. It's the kind of watch that ticks intermittently: once each second the hand sweeps one second-long increment around the dial and then waits one more second to sweep another increment. In the animation, the frequency of the ticks lessens, but the speed at which the hand sweeps each increment stays the same. To be consistent, the sweep-speed needs to slow down just as much as the tick-frequency.