Why Oswald the Rabbit has a mechanical horse isn’t really quite clear in “Ozzie of the Mounted” (1928)—they seem to litter various late ‘20s cartoon series—but an errant spring from inside the animal cuts his head off.
Oswald dances around before the head comes down from the sky. The force of it sinks it into his body.
The head pops back up out of the body and bounces up and down on the top of the body because Oswald presses it into place on his head.
Maybe the most interesting thing about the scene is Oswald struggles to push the spring back into the horse. The spring keeps wanting to bounce up and there are little movements up and down. You feel the pressure Oswald is using. Pretty elaborate for a silent cartoon.
This is a Walt Disney Oswald so Walt is the only one credited, even though he didn’t draw anything. Devon Baxter credits this scene to Ham Hamilton.