Does the flop ever go back?

[pokerdoug1973]

I am a Floor Supervisor and there has always been argument about a particular mistake occasionally made by a dealer that causes me much grief.
In an action game, low limits (3-6 to 8-16) I am called to the table and in formed that there are the usual 8 players for a cap pre flop, and the dealer burns and brings the flop only to hear a player say "I did not call the last bet". They have 3 of the 4 bets out, what is the correct call?
In situation #2 I am called to the table and the dealer informs me that she did not notice the button raised and brings the flop. Visual shows a small pot, seats 4,5,6 have cards as well as the button (seat 1) and there are 2 bets in front of seat 1. The raise was not announced, but I assume it was noticed by at least 2 players because neither the small or large blind have cards. (I know the dealer made a huge mistake when she pulled in the large blinds chips and cards and still did not see the raise.) Whats the call here?
Also, is there a standard rule used in Las Vegas or California card rooms regarding the dealer bringing the flop before action is complete. Does it never go back and the players hands are always killed, even if the dealer fails to announce raises? Or in certain cases is the amount that the player is short considered, and they sometimes be allowed to complete their bet even after seeing the flop?
Mostly I am looking for a determining line so I can make sure all the floors in my poker room make the same decision, each time it needs to made.