Ra appears unmasked for the first time since the original Stargate film. Jaye Davidson, who played the character in the film, retired from acting, so in the season 8 finale Ra was always seen with his mask on. Here is played by Jay Williams, but has no lines and is only seen on wide shots, never in close ups.
The film is dedicated to the memory of Paul McCann, 32, and Anthony Huntrod, 20, of the HMS Tireless, who died in an accident during the filming of the arctic scenes of 'Stargate: Continuum'. The accident was an explosion of an oxygen generator and not related to the maneuvers made for the movie.
Director Martin Wood and Props Master "Evil" Kenny have cameos in the scene in the arctic where Sam and Cam first meet up with Jack. Due to the secluded nature of the filming location, no extras were available.
The scenes in the arctic with the submarine surfacing and submerging through the ice are not special effects. They were filmed live and show the USS Alexandria (SSN-757) breaking through the ice, and later submerging. The captain and crew play themselves during onboard scenes.