Just check the spacing at the back of the tub when you pull it out and it clears the back support. Make sure there's little to no gap between the top edge of the tub and the screen or some of the smaller guys will slip out.

The remedy is the front to back 2x2 on the screen that jasbus mentioned. It is a nice design but it needs testing and tweaking before you fill it with rodents. I know from experience.