Bryant, who is under several guidelines put forth by the team and his adviser David Wells, stemming from a July arrest for a Class A misdemeanor charge for domestic violence regarding an incident with his mother, was unavailable for comment.
One of the conditions he must abide by is to be home by midnight, unless it's been pre-approved by Wells or the team.
Wells confirmed he approved for Bryant to hang out at a nightclub to celebrate his birthday, which is Nov. 4.
"He had a security person there with him and some of his teammates were there too," Wells said Saturday morning before leaving for Atlanta, where the Cowboys play the Falcons on Sunday night.
Bryant, according to Wells, did arrive on time for a Saturday morning walkthrough practice and another source confirmed he was expected to participate in that session.
Bryant is listed as questionable on the injury report with a sore hip. Bryant has participated in some walkthrough practices but he fell down while attempting to catch a pass on Friday.
A photo placed on twitter claimed Bryant, former Dallas Mavericks guard Delonte West and free agent forward Josh Howard were at a Dallas nightclub. The photo was later taken down by a DJ who goes by the twitter handle of DJklassik.
The Cowboys value Bryant's talent, but he's been inconsistent in his play at times this season. Earlier this week he told ESPNDallas it's time to reach his full potential.
"I feel like now, it's about time," Bryant said Thursday. "It's about time."
Bryant has 41 catches for 488 yards with two touchdowns. He's had several key drops, including one that could have led to a touchdown and another on a game-winning two-point conversion, but he's produced two 100-yard games and four games with over 80 receiving yards.
Bryant also made a critical mistake last week in a loss to the New York Giants, where he turned the ball over while fielding a punt and it led to a Giants score. Bryant was taken off punt return duties and replaced by Dwayne Harris.
"I'm not Superman or anything like that," Bryant said this week. "Sometimes I feel like things happen and it's all about how I respond to those bad situations. Do I learn from them? Do I keep making the same mistakes? I feel like I do a good job learning from my mistakes."
Bryant's legal issues sometimes outweigh what he does on the field. The Dallas County District Attorney's office said this week it won't drop the domestic violence charge against him and will continue to explore it.
Bryant hasn't commented on the domestic violence charge.
Cowboys officials were not available for comment regarding Bryant getting permission to be out after midnight.