Play clock expired before snap on big pass by Chiefs’ Patrick Mahomes during rally against Broncos

One of the biggest plays from the Kansas City Chiefs’ late rally to beat the Denver Broncos on Monday night never should have happened.

Replays show that the play clock had expired well before the ball was snapped to Chiefs quarterback Patrick Mahomes on third and 7 just before the two-minute warning in the fourth quarter.

But no flag was thrown, and Mahomes completed a 35-yard pass to Demetrius Harris at the Broncos’ 11 on the ensuing play. Two plays later, Kansas City’s Kareem Hunt scored the game-winning touchdown on a four-yard run.

Broncos coach Vance Joseph said an official told him the Chiefs got the snap off in time before Harris’ big play.

“I disagree,’’ Joseph said after his team’s 27-23 loss.

Some Broncos defenders said an official admitted to them that the play clock had expired before the ball was snapped on that play.

“The ref told us that the ref that was supposed to be watching it just missed it,” linebacker Brandon Marshall said. “He told us that. The ref told us the guy that was supposed to be watching the clock just missed it.”

Cornerback Chris Harris Jr. said he was told the same thing.

“That was crazy, man,’’ Harris said. “It was zero seconds on the clock forever.”

charles.schilken@latimes.com

Twitter: @chewkiii