During Rainbow Man's end credit scene, you see him hanging out with Roll, possibly a date, which can be a reference to the Megas' song "Don't Mess with Magnetman".
Mr. Shin'iri, an enemy found in Jet Man's stage. He's a tourist carrying a suitcase that runs quickly as if he's late for a flight. When he approaches Megaman, his suitcase explodes into a swarm of Pipis for no apparent reason and he runs even faster in panic. It's as silly as it sounds.