When Nanette is looking through the complaint log (28:21), the subject line in one of the complaints is "stop pausing and watch the show".
Series creator Charlie Brooker has not ruled out another follow-up to this. He said he might not be finished with the world of USS Callister just yet, and to "never say never."
When Walton opens a box of Daly's belongings, a Space Fleet comic book, titled "Back for Vengeance," features a treasure trove of Easter Eggs on its cover: Waldo from The Waldo Moment (2013), a glyph from White Bear (2013), and a robotic dog from Metalhead (2017).
The planet at the start of the episode has many rock formations at 45 degree angles. This is reminiscent of Vasquez Rocks in America, made famous largely by many Star Trek episodes (such as the Gorn/Kirk fight in Arena) and spin-off series and films
At around 01:10:00 when the crew of USS Callister is about to face all other players you can hear the legendary internet battlecry "Leeeeeerrooooyyyy Jenkins"