Reid sent referee Tommy Nunez tumbling to the court and was then ejected with 2:56 remaining. That started Utah's rally, which led to a 59-53 victory Sunday night.
"I don't know what he thought on that play," Utah's Jakob Poeltl said. "It's unusual, to say the least."
After stealing the ball from Poeltl, who was driving to the basket, Reid tried dribbling upcourt. But a lunging Poeltl seemed to bump Reid, and the Oregon State forward slipped and fell to the floor.
Reid complained that there was no foul call, and while he got up, it appeared that he made eye contact with Nunez and stuck his right leg out. Nunez went right down.
"It was obviously a fortuitous deal for us," Utah coach Larry Krystkowiak said. "Not a great break for them. It's unfortunate that was part of the game."
Reid was assessed a Flagrant 2, and Brandon Taylor made the free throw to give Utah a 53-52 lead -- its first lead of the game.
The Beavers (11-5, 2-3 Pac-12) were outscored 6-1 the rest of the way.
Pac-12 commissioner Larry Scott is expected to review the incident Monday.
Oregon State coach Wayne Tinkle said he would be looking more closely into the sequence of events.
"I will have to review and discuss the entire play with Jarmal," Tinkle said. "Obviously, we don't -- ever -- want to shed a negative light on our program or university or conduct ourselves in any manner other than first class, on or off the court."
Tinkle said he didn't see the play. He said Reid "swore he didn't do anything." Officials told the coach it was clearly intentional.
"I'm just disappointed, very disappointed," Tinkle said. "It was a hell of a ballgame. It's a shame, just a shame."
The Utes (13-5, 2-3) were able to watch the replay after the game. Dakarai Tucker said that was the first time he had seen that in college basketball.
Oregon State sprinted to an 11-2 lead in the first half and pushed it to 21-8, thanks to three baskets apiece from Malcolm Duvivier and Stephen Thompson Jr. The Utes responded with a 15-10 run, due in large part to seven free throws, but the Beavers led 34-23 at halftime.
"It was a grind the whole game," Poeltl said. "It felt like we didn't play with energy the first half. We didn't get the stops that we needed. Second half, we did a better job on defense. We got running, we got them out of their zone, and we executed better on offense. The shots went in for us a little more in the second half, and that's how you get rolling."
Information from The Associated Press and ESPN senior writer Andy Katz was used in this report.