During the scene where Echo and company are fleeing the pet store, Echo decides to take his pet ape with them. The "Ape" was actually a three-foot-tall chimp who was made to appear gigantic with camera trickery, and perspective shots. When Echo removes the ape from his cage, the shot shows Echo (with his back turned to the camera) unlocking the cage and walking the ape to the truck. The ape appears to be roughly the same size as Echo. This effect was achieved by having dwarf actor Harry Earles (who played "Tweedledee" in the film) play Echo for these brief shots, and then cutting to the normal sized Lon Chaney, making it seems as though the Ape is gigantic.
While getting ready for the role, Chaney remembered a thief he met when he traveled in his youth. He borrowed the man's attitude and mannerism.