The Flyers entered the third period down 4-2, but received goals from Giroux and Wayne Simmonds - and a Save of the Year candidate from Steve Mason - setting the stage for their eventual overtime victory.
Things got off to a thrilling start. After each team traded a couple goals in the first period, the game took a nasty turn when Flyers forward Sean Couturier took a late elbow from Bruins forward Zac Rinaldo.
Rinaldo was ejected, while Couturier did not return to the game.
Mason stopped 16-of-18 shots for his first win of the season, while Tuukka Rask made 32 saves on 37 shots, falling to 1-3-1 on the season.
Flyers head coach Dave Hakstol had no updates on either Couturier or Neuvirth following the game.