Bobby Brink had a goal and an assist, and Joel Farabee and Ryan Poehling scored for Philadelphia. Brink and Morgan Frost scored in the shootout. Samuel Ersson stopped eight of 10 shots in 28:59 before being replaced by Cal Petersen (16 saves).
Danton Heinen scored, and Linus Ullmark, the reigning Vezina Trophy winner as the best goalie in the NHL, made 33 saves for Boston in his preseason debut.
Farabee put Philadelphia ahead 1-0 at 7:31 of the first period with a wrist shot from the left side off a Bruins turnover.
Pastrnak tied it 1-1 on the power play at 12:46 before Poehling’s power-play goal put the Flyers back in front 2-1 at 17:27.
Pastrnak tied it 2-2 at 7:40 of the second period.
Heinen gave Boston a 3-2 lead at 15:00 before Brink tied it 3-3 at 4:07 of the third.
