WARNING: This will contain spoilers for Star Trek Beyond, proceed at your own risk.
Star Trek Beyond isn’t just the third movie in the Kelvin-timeline series, it’s also a Star Trek movie being released for the franchise’s 50th anniversary.
One of the story elements in this movie involves the passing of Spock Prime and how that affects the Kelvin Spock. The younger Spock begins to consider leaving Starfleet and going to New Vulcan to help repopulate his species. After all, one of the reasons why he stayed in Starfleet after the first movie was because he could be in two places at once with Spock Prime living on New Vulcan. But with the older Spock now gone, young Spock wants to help his people.
This changes at the end of the movie.
Kelvin Spock discovers something in Spock Prime’s belongings that makes him decide to stay in Starfleet. It’s a photo of the movie-era Original Series cast, likely from the Star Trek VI time. That’s very fitting as Star Trek VI was released for the franchise’s 25th anniversary in 1991 and it was the final time the entire original cast was on screen together.
It’s just a photograph, but it’s a cool way to pay tribute to the Original Series crew on the 50th anniversary of the franchise in a movie that very much is true to the spirit and fun of the original show.