The former NBA superstar was scheduled to appear in Dallas with 3's Company on Sunday for a game against Team Power but never showed up.
The BIG3 is investigating Iverson's absence from Sunday's game.
Meanwhile, TMZ reported Iverson was also seen at the Sugar Factory restaurant in Rosemont, Illinois, on Sunday night, wearing the same clothes he had on at the casino.
The former NBA MVP was the cornerstone superstar of Ice Cube's BIG3 basketball league, which features former NBA players in a three-on-three format.
But per the Associated Press, Iverson "hasn't been playing very much—he didn't play at all in his much-hyped return to Philadelphia—and the league says in a statement it had no advance notice that Iverson wouldn't attend the game Sunday."
DerMarr Johnson, 3's Company's co-captain, took over as the team's coach for the contest in Dallas.