In a paceline (particularly when you're shorter than most of the other riders) it's not possible to see ahead. You have to trust the rider who's pulling to indicate hazards, and the rider immediately in front of you to pass it down the line.

I'm with Mr. S. Hand signals are good for pointing out road hazards, and for the last person in line to signal to car traffic. Other than that, audible all the way.

Anyway, hope all involved heal up quick.