Mason, forced into the starting role with Tomas Vokoun lost for the season because of a blood condition, was credited with the goal when the Coyotes shot the puck into their own net on a delayed penalty midway through the third period.
Martin Erat, Scott Hartnell, Yanic Perreault and Scottie Upshall also scored for the Predators. Dennis Seidenberg scored for Phoenix.
Canucks 4, Avalanche 3
At Vancouver, British Columbia, Anson Carter tied it with 42.4 seconds left in regulation and Brendan Morrison scored with 36.6 seconds left in overtime in Vancouver's season-ending victory over Colorado.
Todd Bertuzzi and Markus Naslund also scored to help the Canucks win for the second time in the final eight games, a streak that saw their playoff fate sealed by back-to-back losses to San Jose earlier in the week.
With a point in the standings, Colorado locked up at least seventh place in the Western Conference. Alex Tanguay scored twice.
Red Wings 3, Blues 2
At St. Louis, Henrik Zetterberg scored with 9 seconds to play for Detroit.
Zetterberg one-timed a pass from Brendan Shanahan past Jason Bacashihua to give the Red Wings their seventh straight win and their 12th consecutive road victory.
Shanahan added his 40th goal of the season and Nicklas Lidstrom also scored,
Lee Stempniak and Jamal Mayers scored for St. Louis.
Capitals 2, Panthers 1, SO
At Sunrise, Florida, Matt Pettinger beat Jamie McLennan with a low shot in the fourth round of a shootout and Brent Johnson stopped Jozef Stumpel's attempt to lift Washington.
Dainius Zubrus scored for the Capitals in the second round of the shootout, and Florida's Olli Jokinen tied it in the third round.
Gary Roberts scored for Florida in regulation.
Alex Ovechkin, only the second player in NHL history to record 50 goals and 100 points in his rookie year, scored his 51st goal for Washington.
Kings 2, Flames 1, SO
At Los Angeles, Pavol Demitra scored on a breakaway in the second period and had the only goal in a shootout, giving Los Angeles a victory in Luc Robitaille's final home game for the Kings.
Rookie Jason LaBarbera, who has spent most of the season as Mathieu Garon's backup after winning his first seven starts, made a 39 saves. LaBarbera stopped Matthew Lombardi, Tony Amonte and Jarome Iginla in the shootout after Demitra connected with a short backhander on the Kings' first attempt.
The Kings' 41st victory gave them more wins than any season since 1990-1991, when they were 46-24-10 under Tom Webster. Six of the wins were the result of shootouts.
The Kings finished their home schedule 26-14-1, tying a club record for home victories.
Jamie Lundmark scored for Calgary.
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