You can understand Tom’s dismay. First of all, he’s in a comic book, not a cartoon, and thus will be deprived of all the slapstick, frantic elements that made the moving medium his forte. Second, the mice have removed the mechanism of the lock so they can use it like a small front door - a rather needless act, given the speed and agility of mice, and the evident difficulty of getting from the lock to a table. Third, Tom may be wondering why mice have introduced a Pants Situation into things, because if one of them is wearing pants and the other isn’t you have to ask why. Is it the youth of the smaller ones that requires pants for decency’s sake? Are there perverts interested in mice only if they’re young? Is there a ceremony where Papa Mouse says “Now you are a man,” and the mouse removes his pants for good?
Fourth, someone has placed cheese on the table by the door for no apparent reason.
None of these things are bothering him, though. He’s looking at something on the floor. Possibly the bodies of the people who lived in the house, killed by burglars who gained easy entrance through the now-unlocked front door.