The Simple Things (1953)

Continuity mistake: Mickey Mouse is wearing a hat and fishing when a seagull lands atop his hat. The seagull is facing Mickey's right but when Mickey looks down to see their shadows, the shadow of the seagull shows him facing Mickey's left.

Continuity mistake: When Pluto digs up a hole on the beach, he leaves some sand behind him. When Pluto approaches the mussel on the rock, the sand that he dug up a few seconds ago has disappeared.

Continuity mistake: When Pluto pulls the mussel on his tail like a yo-yo, the mussel gets stuck in his mouth and you can see there is nothing on the sand dune behind him. In the next shot, the sand dune now has grass on it.