I was running the box last night as well and we had a funny thing happen as well. Same situation, long TD run and we waited for the H to signal. He never did, so we just took off running because the R had signaled the first down and the offense was looking to hurry up. As we were hauling down the field, the chains were trailing me and running down the sideline. The coaches were out on the field calling the play in, and as they came back, one of them stepped on the chain. It yanked the yard marker out of the guy in front and the one in back fell over the coach.

. Ended up having to set the chains on second down due to this.