Continuity mistake: When Jake is serving the cream he uses his left hand, then right, then left again between shots.
Continuity mistake: When sitting in the brig, the position in which Namani sits changes. She shifts in her seat, changing the letters visible behind her. (00:55:10 - 00:57:45)
Answer: Each new Kaiju is adapted differently, often based upon what has killed previous Kaiju. This is why the Jaegers have such varied designs. If they relied upon a satellite firings rods from space, there would be no defence when a new generation of Kaiju arrived, adapted to this tactic. Additionally, producing a sufficient number of satellites to cover the entire planet would be a huge task, whereas the Jaeger technology already exists.