In Cleveland's win over the Chicago Bulls on Monday, Mitchell committed a lane violation that led to his putback layup that forced overtime.
The league said that Mitchell steps over the plane of the free throw line before the ball touches the basket ring.
The play happened with the Bulls leading 130-128. Mitchell hit the first free throw before sprinting into the key and hitting the bucket to send the game to an extra session.
Mitchell scored a career-high 71 points in overtime to become the 12th player in NBA history to score at least 70 points.
One of the greatest games in recent memory will be overshadowed by the lane violation.
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Donovan Mitchell sets a new scoring record for the Cleveland Cavaliers and becomes only the 7th player in NBA history to score 70+ points in a game. pic.twitter.com/qbOwr3sqyH
Mitchell was 7-of-15 from three-point range and 20-of-26 from the free-throw line. He had a triple-double thanks to 11 assists and 8 boards. Mitchell was able to play 50 of 53 minutes.
Mitchell is currently seventh in the NBA in points per game. He joined the team after five years with the Utah Jazz and is off to a great start.
The Cleveland Indians are in fourth place in the Eastern Conference with a 24-14 record.
Even if there's a loaded field for those honors, the former Louisville star has evolved into one of the game's deadliest scorers this year, and he's putting his name into the NBA's Most Valuable Player and All-NBA First Team conversations. Mitchell is playing at an elite level as the Cavs look to return to the playoffs.