The Panthers were 0-6 in shootouts and 1-13 in games that extended beyond regulation. Olli Jokinen had three goals, his fourth career three-goal game, to boost his team-high season total to 28 for Florida. Two of his goals came in the first period when the Panthers scored four times against goaltender Brent Johnson.
Alex Ovechkin had two goals and two assists for the Capitals, who have lost seven of eight.
After backup goaltender Frederic Cassivi blocked a shot by Jokinen to start the shootout, Washington's Alexander Semin was stopped by Ed Belfour. Stumpel then scored, and Ovechkin missed before Peltonen clinched it.
Down 3-0 after eight minutes, Washington closed to 4-3 after the first. It was 5-3 before Ovechkin scored late in the second and a power-play goal by Brooks Laich tied it with 13:53 left in regulation.
In overtime, a shot by Jokinen hit the left post.
The Capitals and Panthers sit near the bottom of the Eastern Conference standings and have only a mathematical chance of reaching the postseason. With that in mind, both teams dealt talented players to contenders Tuesday afternoon before the trading deadline.
Florida unloaded Todd Bertuzzi (to Detroit) and Gary Roberts (to Pittsburgh). Washington sent Dainus Zubrus to Buffalo and Jamie Heward to Los Angeles.
Hours later, those left on each depleted roster began the task of playing out the schedule. They staged an entertaining performance that belied their stature as the two lowest-scoring teams in the Southeast Division.