"I don't think I've ever been a part of something like that," said head coach Bill Peters. "There's lots of belief in that room.
"It's a resilient group.
"The energy on the bench wasn't great through 40, but it got better as we went along.
"We stayed with it, had the puck lots in the third, and got rewarded."
Andersson scored his first NHL goal, Sam Bennett, Mark Giordano and Monahan also found the back of the net, and Matthew Tkachuk was the conduit to it all, leading the way with four assists.
"I saw what you guys saw," Tkachuk said. "I've been two-and-a-half years now, and that's loudest I've ever heard the 'Dome.
"It was unbelievable. Great atmosphere. You just knew we were going to win it on that first shift in overtime."
Down by two, the Flames pulled David Rittich with more than 90 seconds to play, and Andersson pulled the homeside to within one with a blast from the point, before Monahan tied things up when it seemed all but impossible.
"It was one of the better feelings I've had in my career so far," Andersson said of his big bomb. "It was like a 'finally!' moment. I'm happy I got it, and happy we went away with a big two points, too."
In OT, Gaudreau chopped home a loose puck only moments after Rittich made a magnificent stop at the other end to send the Flames back the other way in transition.
Monahan dished off to Gaudreau in the middle before the hero put a quick shot on goal. Giordano pounced on the rebound and peppered Flyers goalie Anthony Stolarz with a quick whip from the bottom of the circle, and No. 13 was money on the put-back, chipping it home for his 13th of the year from deep in the blue paint.
Considering the Flames were miles better than their Eastern counterparts on this night, outshooting them 41-19, justice was served.
"I think we were all around the net throughout the third period, including the powerplays," Gaudreau said. "We just couldn't find the net.
"We didn't play our best hockey in the first and second but we stuck with it.
"It was fun to play in front of those fans. They were jacked up, we were jacked up"
Mike Smith "wasn't feeling right," according to head coach Bill Peters, and exited the game after the second period after allowing four goals on 14 shots. Rittich tagged in for the third and made four stops the rest of the way.
With the win, the Flames improve to 20-10-2 on the year.
The Flames opened the scoring at 9:13 of the first after wearing the Flyers down in their own end with a dogged shift that allowed the homeside to get a change in on the fly. Fresh off the bench, Tkachuk made a strong play to hold off the check of Shayne Gostisbehere before wrapping the puck in the blue paint and allowing Bennett to bang it home.
"It's exhausting chasing the game but what a great way to finish," Tkachuk said. "That was insane. We you let that fifth goal in, it takes a lot of life out of you - and it did. But we started to chip away.
"On the tying goal, I think the whole bench, along with the fans, was up, clapping and cheering."
Former Calgary Hitmen star - and 2014 first-round pick - Travis Sanheim evened the score in the opening minute of the second as took a feed from Claude Giroux, barreled his way to the net and tucked home a cheeky backhand shot to record his third of the campaign.
Giordano gave the Flames a 2-1 lead with a shorthanded goal at 5:32, but Philly responded with a pair, 32 seconds apart, to grab their first lead of the night.
James van Riemsdyk struck first just 23 seconds after the captain, corralling a bouncing puck in tight and slamming it home to make it a 2-2 game. Just as quickly, Jake Voracek fed a streaking Sean Couturier, whose net-drive was perfectly timed, leaving the netminder with no chance on the tap-in.
And the Flyers weren't done.
Dale Weise took the puck down the right side and floated one on goal. Smith had trouble with it, and suddenly the Flyers were up by two.
All four goals came in a span of two minutes and 11 seconds.
The Flames got one back nearly the midway mark of the stanza, as Tkachuk teed up Monahan in the slot, and the Flames' leading goal-getter made no mistake on the one-timer. Gaudreau made it all possible with a 'wow' play at the blueline, whipping a backhand pass to Tkachuk after making a great play to gain the zone.
Couturier looked to have put this one away with a shorthanded goal at 11:10, but the resilient Flames had a little magic left and made memories with 19,000-plus on hand to enjoy it alongside them.
"Just a resilient effort from all the guys," Andersson said.
"It's a really good feeling when the fans are going like they were, too."
