Revealing mistake: Later into the film Roger realises that his aunt's paintings hold some significance to the whereabouts of his missing son. He removes a cloth from the top left of a painting revealing an image of his son trapped in his bathroom cabinet. Note the cabinet door is the wrong way round to the one in his bathroom.Paul Andrews
Revealing mistake: Last scene in the movie is Peggy Sue waking up in the hospital. The very last shot of that scene is of the camera backing up from what appears to be a mirror. If you look closely, it isn't a mirror at all, it's actually a window made to look like a mirror complete with another set of actors to mimic the stars of the movie's actions.
Revealing mistake: When Egg Shen helps the others escape by using a crossbow-and-winch device, he fires the bolt into a stone. When the bolt digs in, the stone shudders slightly (since its made of wood or plastic, and no fixed part of the floor).
Revealing mistake: When Danny DeVito brings home the 'bigger dog' he says for the new dog to go eat the little dog that always bothers him. He lets the dog go and the dog goes after the little one. But when they show the dog chasing the little one he almost runs right past him. There must have been a trainer on the other side of the set calling the dogs to come over because he wasn't chasing the little dog. (00:40:30)
Revealing mistake: During their first confrontation with El Guapo, the Amigos start riding around and firing their guns in the air. Look at the difference in speed between the wider shots (with stunt doubles) and the closer ones, which show the actors themselves. Not only are they suddenly moving much slower in these closer shots, but it so very obvious that they are on mechanical horses by the movement.David Mercier