Both players have MRI tests scheduled for Monday.
Bradley left the field on his own after being hurt about halfway through the session. The extent of his injury wasn't immediately known, though trainers appeared concerned about it.
Bradley had 108 tackles in his first full season as a starter last year. He's the primary signal-caller on an Eagles defense that already lost veteran safety Brian Dawkins in free agency.
Hobbs, acquired in a trade with the New England Patriots, is competing with Sheldon Brown for a starting job.
A total of 31,786 fans came out to Lincoln Financial Field to watch the inaugural Eagles Flight Night.
Copyright 2009 by The Associated Press