Olive snatches away a letter from Popeye, but it remains in his hand and then suddenly disappears.
In one scene, the lights in a darkened room were supposed to come up and reveal Olive and Wimpy. But the animators forgot to make the room dark. Instead, in a room flooded with light, we hear a light switch flick on and instantly Olive and Wimpy appear.
Brutus has his foot on one end of a plank as he forces Popeye to walk it. But in one shot, Brutus has his foot perched in the air, while the plank has disappeared.
Popeye and Brutus each bounce up and down on opposite ends of a plank. In one shot, Popeye falls onto nothing but goes back up in mid-air anyway. This sort of thing often happens via cartoon magic, but it's clear in this shot that Popeye's mid-air bounce was merely an animation mistake.