"We should have put the game away in overtime," Voracek said. "We had three or four Grade A chances. Unfortunately, Rask stopped them. And obviously shootout is shootout."
Rask's best two saves in overtime were on a backhand by Voracek in close at 1:29 and against a wrist shot by Kevin Hayes at 3:55.
"The first one, I mean, I saw Voracek was all by himself in the front of the net," Rask said. "The [defenseman] (Travis Sanheim) kind of shot a floater in there. [Voracek] made a good play just trying to tip it in my five-hole, and the rebound was lying there, so I just tried to get extended as much as possible, and I think it happened to hit my glove there.
"And then the second one, you see that develop. The guy was kind of slowing it down on the wing, and [Hayes] was driving the net wide and made a good play, but I just happened to extend my leg there."
The teams will play again Saturday in Boston.
Travis Konecny scored on the power play to give the Flyers a 1-0 lead at 6:17 of the second period. It was his fifth goal, tied for the NHL lead with Tyler Toffoli of the Montreal Canadiens and Bo Horvat of the Vancouver Canucks, and the first power-play goal allowed by the Bruins this season after 15 straight kills.
Van Riemsdyk made it 2-0 at 17:31.
Jack Studnicka scored his first NHL goal to cut the lead to 2-1 57 seconds into the third period. It was the first 5-on-5 goal of the season for the Bruins.