I was wondering if the chu sound was a reference to Chuu Chuu Rocket

Nah, Chu Chu rocket was referencing the japanese sound mouse make. So its more of an "old as time" joke.

Krugger said:
I was wondering if the chu sound was a reference to Chuu Chuu Rocket

Ten to one it's the other way around. The game's about mice escaping cats, isn't it?

As for the image itself: Wasn't expecting this, even if it makes perfect sense. Marisa, you perv.