Woke up and he's nowhere to be seen... then right by the cage: BOOM. (Can't leave the cage open because his brothers in there) [youtube=https://www.youtube.com/watch?v=_TCEl1hz_vc]
My wife had a rat escape when she was younger. I suggest laying out yogurt drops or even a bit of yogurt or cheerios something that'll tempt him out of hiding if he hasn't run away. I think they also have live traps
Something like this [youtube=https://images-na.ssl-images-amazon.com/images/I/61uwNDEfz9L._SL1024_.jpg]
Maybe you can make a reality show over the escaped rat. Laughing to myself because my sons gerbils would escape. And Mom would scream and yell, and finally laugh.