During the big stunt, the character of Seth assists Logan and Rory at the top of the tower. They talk for only a few seconds before jumping to the ground. In the shot of people celebrating that were already on the ground, Seth is shown which would have been impossible unless he jumped before the rest of the group (which would have been pointless since the big stunt is always done as a group, not a lone participant).
While Rory and Logan are climbing the tower, there is a safety line visible from the below shot.