Stargate: Continuum

SG-1 and Jack O'Neill attend a Tok'ra extraction ceremony for Ba'al, the last of the Goa'uld System Lords. Ba'al claims, however, that he is merely the last clone and that the real Ba'al has a fail-safe plan. The real Ba'al travels back in time to 1939 Earth and massacres the crew of the Achilles, the ship carrying the Stargate to the United States. The captain of the Achilles lives long enough to drop the bomb Ba'al left overboard and keep the ship from being destroyed. In the present, people and objects start disappearing, including Vala Mal Doran and Teal'c. Jack is killed by the clone, but Samantha Carter, Daniel Jackson and Cameron Mitchell reach the Stargate. They are surprised to emerge inside the derelict Achilles, which has drifted to the Arctic — Ba'al's actions have created a timeline in which the Stargate Program never happened. After escaping from the sinking Achilles, they are rescued by a team led by Colonel Jack O'Neill. Although General Landry believes their story (after intensive interrogation), they are denied permission to change the timeline. In the alternate timeline, Daniel is still trying to convince people about his theories of the pyramids, Carter died in a space shuttle accident and Mitchell does not exist at all because his grandfather was the Achilles captain. The three are forced by the authorities to lead separate lives, with no contact allowed between them.