Continuity mistake: When the main characters first meet up with the old terminator at his residence, Sarah tries to turn her shotgun on him, but is stopped. Instead, the round goes off punching a hole in a wooden ceiling of the front porch. The resulting debris lands on Arnold's T-shirt, standing out because of the T-shirt's dark color. Several times the camera angle changes and the debris appears and disappears several times throughout the shot. Most notably a splinter of wood on his shoulder.
Continuity mistake: When John is killed, the stool on the right moves away between shots.
Answer: Skynet and Legion were both developed for identical purposes: defense network artificial intelligence. It stands to reason they would both evolve in similar ways. Since both Skynet and Legion were fighting a similar human resistance, they both developed similar infiltration units.
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