Visible crew/equipment: In the scene When Dobbs is panicking as he searches for the body of his not-so dead partner, who he had tried to kill the night before, he stumbles left and right. The camera pans a bit to far revealing the studio lot, building and fence, and a crew member sitting by a truck or machine.
Factual error: Based on the lottery poster, the movie is set in 1925. During the scenes in Tampico, numerous newer cars (closer to the 1948 filming) are present in the background.
Continuity mistake: When Humphrey Bogart dunks his head in the watering hole, he leans over far enough that his hat is almost entirely submerged. In the next shot, he sets his hat down beside him and only the front portion is wet.
Revealing mistake: When Howard and Curtin chase Dobbs, they pass a dead donkey which is obviously breathing, and the rope used to tie its legs together is visible too.