"No idea, but I've been caught on dumber cameras in the middle of nowhere." He pulls the gate open and the creaking echos. "Might have some kinda motion sensor, too."

So in other words, he's pretty sure they were on candid camera, but he's not going to worry until the men in white are on top of them.

"Thinkin' it means we're almost out. Gotta dump out somewhere soon." Even though it's damp, the further they move, the less actual water there is. That's how he can tell that they're leaving the city. There probably isn't a dump-out, because they wouldn't have water to spare for that, but he thinks it'll still be built like that. It's got to lead somewhere or they wouldn't bother locking it.