Here's one for the mil guys that shocked me!

On reserve (like being on Bravo, you have a three hour call out), they can't call you up one hour before your reserve period ends and have you go fly a 16 hour day. Your reserve pairing may be for four days, but you only sit for one day at a time (unless you get called in, then it's just a regular trip), so say your reserve period for that day ends at 1700, you're not going to get a call at 1600 to go fly a trip that day. Plus, like Joey says, you're auto-released 6 hours prior to the end of your final reserve day.
I'm sure it's like this at other airlines, but this one was a huge difference between mil vs. 121.