Bäckstrom, who has been sidelined with major hip problems in recent years, played his second game after returning from hip surgery this summer and picked up his first point of the season.
Washington's goals were scored by Marcus Johansson, Garnet Hathaway and TJ Oshie.
The last played by Bäckström in the third period.
Philadelphia's Travis Konecny completed his second career NHL hat trick when he scored an empty net goal with 13 seconds remaining.
He has thus scored points in ten games in a row.
Philadelphia's Scott Laughton and Owen Tippett each scored.
Nashville's Filip Forsberg scored and tied the score at 1-1 in the second period in the meeting against Toronto.
But Toronto's Mitchell Marner tied it with 1 minute 15 seconds left, played by William Nylander.
The match ended 2-1 to Toronto.
CLIP: Nicklas Bäckström made a comeback - after almost nine months (January 9, 2023)
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Nicklas Bäckström was back in the Washington Capitals jersey last night.
Photo: Terrance Williams/AP/TT