In the scene where Mercutio has just died on the beach, Romeo is sitting on top of him, pulling his body around. He then gets up and staggers back a few steps, clutching his head in dispair, before running off to the car.

He must have stood around a bit longer than previously rehearsed or agreed, because the character of Benvolio kneels down by Mercutio's body when Romeo stands up, then suddenly whips his head around in the direction of the car - as if shocked and surprised by Romeo's "sudden" exit.....when in fact, Romeo is still standing right there next to him!

Ooops!