Hi Ron,
I have always been meaning to ask you since you never commented on this bug in any of the speeches you've given about Maniac Mansion in recent years.
I remember that in the C64 Version you were able to actually walk up the plant even while it was small if you were clicking just the right spot on the hatch. You just couldn't exit the room. Similarly you could walk "up" the garage door while it was closed by just clicking on it enough. Do you remember this bug and/or what caused it?