Foxed by a Fox (1955)

A hunter and his dog are chasing a fox. The fox reaches out of the screen, grabs a pencil and eraser from the artist, and then proceeds to animate the film to suit his own needs. He erases the dog's legs and draws him shorter ones. Using the pencil he draws a variety of dangers, traps and hazards that frustrate the hunter, including rapidly changing the backgrounds. But the tables are turned when the hunter grabs the pencil.