No, and this isn't what Facebook did internally. "Lockdown" was more of a way of thinking about the problem and cover for working longer hours rather than literally locking the doors to prevent people from going home.
Eh, they probably can't legally make you stay, but they can certainly fire your ass for leaving.
>Eh, they probably can't legally make you stay
I mean, they absolutely cannot. We have a term for that; it's called 'kidnapping'.
Actually, its "false imprisonment". "Kidnapping" is different.
Depends on the state, but I don't think you're correct.
Under False Imprisonment FB could lock the employees in, just as long as the employees didn't know they were locked in at the time of being locked in (i.e. they only found out later after FB unlocked them) ;)