Geoff Snider had a hat trick for Calgary (1-1), while Shawn Evans and Karsen Leung also scored.
Sean Pollock replied with a hat trick for Colorado (1-2). Adam Jones, John Grant Jr. and Drew Westervelt had two goals each, with Jordan McBride and Joel Dalgarno chipping in with singles.
Calgary's Mike Poulin made 34 saves in net. Tye Belanger and Dillon Ward meanwhile combined to stop 41 shots for the Mammoth.