McCarron was seen limping after a play during an 11-on-11 drill ended in what would have been a sack. The play was whistled dead because defenders are not allowed to make contact with quarterbacks during practice.
Athletic trainers examined McCarron's lower right leg before he returned to participate in another 11-on-11 drill later in practice. McCarron again spoke to a trainer after that drill, slamming his helmet down in apparent frustration.
Peterman appeared to be hurt on his final play during a live-action drill at the goal line to end practice. After being tripped while attempting a handoff and falling on his right arm, Peterman spoke to trainers and later was seen testing his throwing arm.
Peterman, who started the Bills' preseason opener Thursday, led the first-team offense Sunday as part of a rotation between him and McCarron, who led the first-team offense in practice Friday. Rookie Josh Allen also saw occasional practice time Sunday with the first and second teams.
The Bills return to practice Monday in advance of their next preseason game, Friday against the Cleveland Browns. Coach Sean McDermott declined Sunday to name a starting quarterback for that game.