I've recently been attempting some 100% runs, and I've noticed that I can never seem to pull off the text skips going in and out of the hidden room through the mouse hole. Usually when I try, the animation of Luigi spinning the vacuum plays (after catching the boo), followed by the animation of Luigi being sucked into the mouse hole. But after this happens, Luigi appears back inside the original room, and E. Gadd's text comes up like normal. I'm not sure if it's a timing issue, a placement issue, or whatever else, but I'd appreciate some feedback on what I might be doing wrong.

It probably doesn't make a difference, but I've been running on a U.S. disc with a U.S. Gamecube.

You can only perform the glitch on the Japanese version of the game.

What GlitchDoctor said, this is a Japanese exclusive trick.

Ah, thanks guys!