At the Federation Day Centennial, an uninvited guest disrupts Spock and the crew's reflections.

Anson Mount (Captain Christopher Pike)
Ethan Peck (Lieutenant Spock)
Jess Bush (Nurse Christine Chapel)
Christina Chong (Lt. La'an Noonien-Singh)
Celia Rose Gooding (Ensign Nyota Uhura)
Melissa Navia (Lt. Erica Ortegas)
Babs Olusanmokun (Dr. Joseph M'Benga)
Martin Quinn (Lt. Montgomery Scott)
Rebecca Romijn (Lt. Commander Una Chin-Riley)

John de Lancie (Voice of Wedding Planner's father)

Cillian O'Sullivan (Dr. Roger Korby)
Rhys Darby (Wedding Planner)
Melanie Scrofano (Captain Marie Batel)
Dan Jeannotte (Lt. Samuel Kirk)
Mynor Luken (Beto Ortegas)
Chris Myers (Ensign Gamble)

Myles Dobson (Young Vulcan Bartender)
Kira Guloien (Kelzing)
Alex Kapp (U.S.S. Enterprise Computer)
Ron Kennell (R'ongovian Delegate)

• This episode takes place three months after the season premiere, with the U.S.S. Enterprise having spent the time in repairs at Starbase 1.
  
• Nurse Chapel returns to the Enterprise after a three month sabbatical with Dr. Roger Korby, and the two are now dating.
  
• Dr. Roger Korby first appeared in the classic episode "What Are Little Girls Made Of?".
  
• Though unnamed in the episode and end credits, executive producers and showrunners Henry Alonso Myers and Akiva Goldsman have stated the character played by Rhys Darby is intended to be Trelane from the classic episode "The Squire of Gothos", and his father is Q.