- Katherine Heigl as Tully Hart
- Sarah Chalke as Kate Mularkey
- Ben Lawson as Johnny Ryan
- Beau Garrett as Cloud
- Ali Skovbye as Teenage Tully
- Roan Curtis as Teenage Kate
- Yael Yurman as Marah Ryan
- Brandon Jay McLaren as Travis
- Chelah Horsdal as Margie Mularkey
- Quinn Lord as Sean '74
- Jason McKinnon as Sean
- Paul McGillion as Bud
- Synto Misati as Robbie '74
- Thomas Cadrot as Robbie
- Patrick Sabongui as Professor Chad Wiley
- Tara Wilson as Julia
- Brendan Taylor as Mutt
- Bronwen Smith as Rita
- Tebo Nzeku as Emma
- Anthony Ames as Man with Margie
- "We Got the Beat" by The Go-Go's: In the '80s, Tully showers the bathroom with hair spray and then arrives at a college party.
- "Love to Love You Baby" by Donna Summer: Kate watches Johnny fix the sink in the 2003 setting, and then shares an intimate moment with him on the kitchen floor.
- "Something Old, Something New" by Lonnie Russ: Kate's parents play their favorite song during a dinner scene with Tully.
- "Time After Time" by Cyndi Lauper: Marah plays the piano at a school event. A cover version of the song plays at the end of the episode when Tully realizes that she's pregnant.
- "Every Song in Firefly Lane Season 1" ScreenRant February 4, 2021