I like the episode, I have a few problems with it.
One, is everyone deaf? Drilling through concrete is a quite job. I know a casino can be noisy, but come on. When ever you drill through concrete it reverberates through everything. Someone should have heard something.
Two, Mike went to investigate the truck parked there all day, but got called away. Well that night it was still there, yet no red flags when off, like "Hey that truck has been parked in our loading dock for like 12 hours, should we call the company that owns the server asking what the hell they are doing here all day?". Three, I know compressed gas is well compressed and can expand a lot, the tanks they have could probably fill a good 4-5 bedroom house and still have left over, but this is a giant casino, there is no way those 2 tanks have enough gas to fill the casino to the concentration to knock people out. Also it seems to spread way to fast, this casino is suppose to be the size of a large strip hotel. They have used the Monte Carlo and Mandalay Bay for shots in the early days of production and both are rather sizable, spraying gas on one side of the casino wouldn't reach the other side of the casino let alone fill it to knock people out for many minutes if not longer.
Overall very good episode and I can't wait to see what happens.