This video showcases unused behavior in the original Ape Escape for PS1.

The cars on the street in TV Tower can be ridden with glitchy collision and instantly kill Spike when running him over. Normally, the street is inaccessible, but it can be reached with the infinite jump glitch. Interestingly, the level intro shows the street and cars, so at some point during development it's possible the player was meant to go there.

More details on TCRF.