For the 1994–95 season however things did not work out and after just 5 games Montgomery was released by the Canadiens. Later in the year he was signed by the Philadelphia Flyers and skated in 8 regular season contests and 7 playoff contests with the Flyers. Montgomery is credited with nicknaming the dominant line of John LeClair, Eric Lindros, and Mikael Renberg the "Legion of Doom".
Following college, Montgomery was signed by the St. Louis Blues. For the 1993–94 season he skated in 67 contests and scored 20 points, both NHL career highs. Following the season the highly-touted Montgomery was traded to the Montreal Canadiens for Guy Carbonneau.