Erik Johnson, John Mitchell and Matt Duchene also scored as the Avalanche won for the fifth time in six games to leapfrog Dallas in the Central Division standings.
MacKinnon's score with 8.4 seconds left in the second was part of a three-goal period for the Avalanche. They came out fast to start the third, too, with Duchene scoring just 12 seconds into period.
Introducing the new official NHL App, available for iPhone, iPad and Android smartphones and tablets. A host of new features and improved functionality are available across all platforms, including a redesigned league-wide scoreboard, expanded news coverage, searchable video highlights, individual team experiences* and more. The new NHL App on your tablet also introduces new offerings such as 60fps video, Multitasking** and Picture-in-Picture.
*Available only for smartphones
** Available only for suported iPads