In the Big Top Experience there is a gun that shoots balls you can use. it turns out the balls can move the player slightly. i have not been able to exploit this yet but i am 100% sure this gun could be used to clip out of bounds.

Yep my thoughts exactly:

On the stairs in the lobby before you meet Big Top for the first time I was able to shoot a ball, it bounce back, me land on it and it then launch me into a corner, soft locking myself.

Given the janky colisions in this game, it could potentially be used to get OOB.

I've found that by trapping a ball between the player's hitbox and a corner of a wall there's a consistent jittery motion that pushes the player around a lot. So far I've only tried with 90 degree corners, and it's worked with every one I've tried. Not sure if it works with other corners, though.