Dubois fired a rolling puck past goalie Jake Allen for his fifth of the season.
''It is a very special place to play,'' said Dubois, from Sainte-Agathe-des-Monts. ''There are no fans so it takes away a little bit of that this year but I have a lot of friends and family who were watching the game.''
Winnipeg improved to 5-0 in overtime this season, and Montreal fell to 0-4.
Allen stopped Kyle Connor on a breakaway in overtime before turning away Blake Wheeler on a 2-on-1. Winnipeg's Connor Hellebuyck also came up big on Montreal's Paul Byron in the extra period.
Montreal's Corey Perry forced overtime with his third goal of the season at 18:36 of the third. It came with Allen on the bench for the extra attacker.
Paul Stastny put Winnipeg ahead 3-2 with his second goal of the game at 3:39 of the period. All four of the Jets' goals were scored by Quebec-born players.
''It's always special, it's always fun to come back here,'' Stastny said. ''It's always a special place to play and for me it's where I scored my first goal. It's a cool place with a lot of history and you always kind of enjoy it. As I'm getting older now in my latter years you don't know how many more game you'll play here so just have fun with it.''
Hellebuyck made 33 saves, and Mathieu Perreault also scored for Winnipeg in the first of five straight road games. The Jets have won six of seven to improve to 15-7-1.
Brendan Gallagher and Tyler Toffoli also scored for Montreal. The Canadiens are 1-3 under interim head coach Dominique Ducharme and 10-7-5 overall.
''We can cut down on those mistakes for sure,'' Ducharme said. ''We don't need to go into details . . . guys know right after the play. We'll clean that up. Maybe sometimes it's about luck a little bit but something we control is high-percentage plays. Doing those things all the time, then luck is more on your side. We had too many of those (mistakes) tonight.''
The teams will meet again Saturday night in Montreal.
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