Carcone tied it 1-1 at 16:55, taking a touch pass from JJ Peterka and burying a wrist shot from between the circles to the blocker side.
Crouse put Utah ahead 2-1 just 45 seconds into the second period. Weegar's shot from the point hit traffic in front, and Crouse backhanded the loose puck into an open net.
“It's tough to lose that game 3-3 in the third, but we can be proud about our regular season,” Crouse said. “We set a goal at the start of the year to get to the playoffs, and we made that happen. So now I just turn the page and get ready for Game 1.”
The Mammoth appeared to make it 3-1 at 1:26, but St. Louis challenged the play for goaltender interference on Brandon Tanev and the goal was overturned after video review.
Thomas evened the score 2-2 at 8:14. Holloway backhanded the puck into the slot from the right of the net, and Thomas sent a snap shot past the outstretched glove of Vejmelka.
Thomas scored his second of the period to put the Blues up 3-2 at 11:07, redirecting Cam Fowler's pass from the blue line to the blocker side from in front.
“I'm proud of this group though. We didn't roll over and just give up the last bunch of games,” Thomas said. “We went on a four game win streak to end the season and (that’s) something to hold their heads up to.”
Yamamoto tied the game 3-3 at 18:52 when he put a wrist shot past Hofer's glove from the slot.
St. Louis defenseman Colton Parayko played his 800th NHL game, joining Bernie Federko (927) and Barret Jackman (803) as the only players to reach the milestone with the franchise.
“It's pretty special,” Parayko said. “To be able to do it here in St. Louis and a special team, special organization. There've been so many great players and coaches that came before me and that I've got to play with, so just trying to take that and keep passing on all the good stuff down through and just keep that going.”
NOTES: Buchnevich has four points (three goals, one assist) in a four-game streak. ... Keller extended his franchise-record point streak to 10 games (four goals, 16 assists). ... Crouse tied his career high for goals in a season with 24, which he set during the 2022-23 season with the Arizona Coyotes. ... Utah dressed 11 forwards and seven defensemen. ... The Mammoth played without forward Dylan Guenther (undisclosed) and defenseman Sean Durzi (upper body), who was injured in a 5-3 win against the Winnipeg Jets on Tuesday.