Muzzin tied the game 1-1 on the power play at 4:09 of the third period with a slap shot through a screen from the point by Smith's blocker.
"One point isn't satisfying enough for us right now, and to have a lead in the third and give it away, that's where it hurts," Flames forward Matthew Tkachuk said.
Monahan put the Flames up 1-0 at 14:03 of the first period. He took a drop pass from Micheal Ferland before finishing a give-and-go with Johnny Gaudreau by shooting past a diving Kuemper. The line has combined for 36 points (11 goals, 25 assists) in the past 10 games.
"What a goal that was," Tkachuk said. "We weren't getting too much offense going, and it was a great play by them to get us the lead. They were playing good. They were creating. It was just unfortunate that the rest of us couldn't get one either."
Smith made a glove save on Alex Iafallo's one-timer at 10:57 of the second period, and Kuemper made consecutive saves on three Monahan shots in a span of four seconds, starting at 15:34 with Calgary on the power play. Monahan also hit the post, and was stopped by Kuemper on a follow-up attempt at 16:04.
"[Darcy] was awesome," Pearson said. "He kept us in the whole night and made some really big saves for us."