Mittelstadt made it 4-1 at 9:21, redirecting an Elias Lindholm centering pass through the five-hole.
Minten made it 5-1 at 15:59 with his second goal of the season. The 22-year-old signed a seven-year, $50.4 million contract ($7.2 million average annual value) with the Bruins on Sept. 8, which begins next season.
"I feel good out there," he said when asked to compare his game to a season ago. "I feel fast and feel like I can make plays and contribute, while still being good, and responsible defensively. I feel like my game is growing, for sure."
Flyers forwards Travis Konecny (lower body) and Cam York (upper body) did not play and are each day to day. Prior to the game, the Flyers announced that defenseman Rasmus Ristolainen was placed on injured reserve retroactive to Oct. 3 with an upper-body injury and that forward Nikita Grebenkin had back surgery and will be out at least four months.
"You've got to stick together," Flyers coach Rick Tocchet said. "We're at the bottom. We're in the muck right now. Hopefully we get some healthy bodies back, but you've just got to stick together. There's no other answer. We've all been, in life, in a situation where you're in a fox hole and we need some people to sit in a foxhole and stick together."
NOTES: Bruins defenseman Charlie McAvoy completed his six-game suspension, a ban he received for slashing Buffalo Sabres forward Zach Benson during Game 6 of the Eastern Conference First Round last season. He is expected to make his season debut at the San Jose Sharks on Tuesday. … Swayman tied Andy Moog (136) for the eighth-most wins in Bruins history. Peterka got his 200th NHL point (94 goals, 106 assists) and became the third-fastest Germany-born player to reach the milestone behind Tim Stutzle (229 games) and Leon Draisaitl (260 games).