This is one of my biggest fears, in fact almost every month I have at least one rat escape when I'm cleaning tubs and moving rodents from one tub to another, it happens pretty easy when you have hundreds of rodents to move. Just yesterday I had a pregnant female get out, she bolted out of the tub and got between the levels in my ARS rat breeder rack. Luckily I can stick my arms in there between the levels and trap her with my hands. I couldn't imagine what would happen if a mom and babies got in a spot where I couldn't get them and I ended up with a rat infestation in the house, OMG. When a rat gets out I drop everything and tear apart the room until I track them down.
I'd suggest getting a few live traps. I found this on Amazon, looks like I could use a few as well. I would go with the dual door model and set them up along the walls. If I ever expand to the point where I build my own rodent facility I'm going to install automatic traps all over the place.
https://www.amazon.com/AB-Traps-Pro-...pSrc=srch&th=1