Multiple SG-1s show up at Stargate Command, leading the "real" team to conclude that they have each been inadvertantly displaced from different parallel realities. When SG-1 travels to an Asgard ...
Asgard is Earth's most powerful and reliable ... The Goa'uld were first introduced in the original Stargate movie, so it made sense that they would also be the first villains of the franchise ...