Running back Maurice Jones-Drew was carted to the locker room in the first half with a left foot injury. Jones-Drew was shown receiving a tape job on his foot before briefly re-entering the game. Then he took a cart ride.
Rashad Jennings replaced Jones-Drew, who returned to the Jacksonville bench on crutches to begin the second half.
"It was a routine tackle, it just got rolled up," Jones-Drew, who was injured after a 3-yard run on the Jaguars' first play from scrimmage, told The Associated Press. "It didn't feel right, so I didn't want to go out there and hurt our team if I'm not feeling right."
Later in the first half, Jaguars quarterback Blaine Gabbert took a shot to his left (non-throwing) shoulder. He was seen wincing in pain, but he stayed in the game for two more drives. Chad Henne ultimately replaced Gabbert midway through the second quarter. Gabbert later returned to the sideline once the second half began, but he also was out of uniform.
Gabbert has struggled to start his second season, but there hadn't been any serious quarterback controversy in Jacksonville because Henne struggled even more throughout training camp and the preseason. Henne was 9-of-20 passing for 71 yards and no touchdowns against the Raiders.
Jaguars coach Mike Mularkey said after the game that he didn't know the extent of Jones-Drew and Gabbert's injuries. NFL.com and NFL Network's Steve Wyche reported that both players will be fully evaluated once the team returns to Jacksonville from Oakland.
Fullback Montell Owens also left Sunday's game after hurting his left shoulder, the Jaguars announced.
Follow Gregg Rosenthal on Twitter @greggrosenthal.