"34.7 Verification of Time - Any loss of time on the game or penalty clocks due to a false face-off must be replaced as appropriate. The Video Goal Judge may be consulted to ensure the time is accurately replaced.
In the event of any dispute regarding time, the matter shall be referred to the Referees for adjudication and their decision shall be final. They may use the Video Goal Judge to assist in rendering their final decision. (See Rule 38 – Video Goal Judge.) The Game Timekeeper shall assist to verify game time using an additional timing device (League-approved stopwatch).
In the event that clock fails to operate when play resumes, the on-ice officials may elect to stop play provided there is no imminent scoring opportunity or wait until the next legitimate stoppage of play. In cooperation with the Game Timekeeper and the Video Goal Judge, the clock is to be re-set to the appropriate time.
In the event that a video replay shows a goal was scored prior to the play being stopped, the Video Goal Judge will inform the Game Timekeeper and Official Scorer of the time of goal and the amount of playing time left to be reset on the game clock."
I don't think any of that says what would have happened had Boston scored in that final five seconds (which they shouldn't have had), other than just that the ref gets to decide and his decision is final, and after a quick look I can't find any other rule that would say what would have happened. So, I think that just means the referee gets to decide. But what would the ref have decided? I wouldn't have wanted to be that ref.
I've always been really superstitious in the playoffs in how I watch the game since I will never get to watch live due to work: DVR delay and avoiding twitter, coming in live in progress. Tonight I decided twitter only and do not watch and they pull off a win despite being outplayed. Guess I need to find something to do out of the house on Saturday.