Continuity mistake: When Rosencrantz and Guildenstern meet the Players on the way to Elsinore, the sky around them changes. In the shots of the players, it's gray sky, possibly approaching dusk, and in the shots of Rosencrantz and Guildenstern, it's pitch black. (00:13:20 - 00:14:40)
Continuity mistake: When Guildenstern tells The Player what he thinks is wrong with Hamlet ("A man talking sense to himself..."), he is holding his hands together in the close-up but not in the wide shot. (01:03:40)