NFL rules

If a team scores a touchdown while the clock runs out in the 4th period and the point after will have no bearing on the outcome, is the game over without the try ? Does the scoring team get a choice ? Must the scoring team attempt the try ? With contract incentives I have a feeling the team must attempt the try.

During the Monday night game against Miami a few weeks ago, the Jets were ahead 41-7 when the Dolphins scored as time ran out. They kicked the extra point with 0 time left on the clock. I guess it has to do with point differential and tie-breakers.

Seems like I remember a Patriots game a few years back (I think they were playing Buffalo) where they scored the game-winning TD with no time left. Buffalo walked off the field before New England could attempt the PAT; they made them run it anyway so they snapped the ball to Viniateri and he ran it in for two.