I think it may be possible to roll a sprag and have the transmission lock up, or at least the to decelerate the car, when you put it in 2nd. I never put a car in 2nd gear at the finish line driving an automatic, and Kevin does not do it with the Camaro.
Last year, I had the luxury of just stepping on the clutch after I crossed the finish line. Of course, no better than my lights were, I only got to cross the finish line a couple of times. And I'm not driving this year, either.