Orton, who started and played into the second quarter, passed for 135 yards, while Quinn, who played the entire third quarter, ended 10-of-16 with a 24-yard TD pass to Britt Davis. Tim Tebow played the final quarter behind center for the Broncos, completing one for 10 yards.
Willis McGahee scored receiving and rushing touchdowns in Denver's exhibition win.
Buffalo's Ryan Fitzpatrick completed 6-of-16 passes for 44 yards while playing the entire first half.
Tyler Thigpen entered after that and went 11-of-20 for 118 yards and a 13-yard score to Felton Huggins.