WRONG

Not yet, keep digging, keep digging... :p

I GIVE UP

ok dude, chill. sometimes i can't help but think that way, plus it's all i have at the moment... so it's not like i had some sort of fantastical solution to contribute.
Give us one hint please.
Is a play on words an element of the solution?

maybe the bus pulls into the stop, and the mouse let's the ant on first cause it's smaller and is thus considered "physically disabled", however because the driver cannot see either of them given their small stature, doesn't stop for long enough for them both to climb aboard.

The mouse is afraid of the automatic doors because they remind it of a mousetrap.

The ant is actually that kid from Ant Bully and wants to go home. While Jerry doesn't wanna board the bus since he has his own little vehicle.

The mouse has eyes and can see the route number of the bus and knows it's going to pest control while the ant is incapable of seeing anything.

If the ant got in the bus, maybe that particular bus was for ants and thus completely unsuitable for a mouse to ride in.

O.o you people scare meh