"WWE RAW" Arena -- We Don't Have a Mice Problem!

The arena that hosted WWE RAW last night wants to make it perfectly clear ... they do NOT have a rodent infestation -- they were just the innocent victim of a mouse prank.

Ernie Hahn -- GM of Valley View Casino Center -- tells TMZ, the mouse that made a cameo during a bout between Alberto Del Rio and John Cena on last night's show was a white "feeder" mouse bought from a store ... NOT your average wild gray/brown variety.

Ernie claims the color theory proves it wasn't an in-house mouse -- and even if it were, it wouldn't survive long ... because according to Ernie, the arena employs a full-time pest service to keep critters under control.