In Die Hard 3: Die Hard with a Vengeance, we see that officer John McClaine of the NYPD has actually left the LAPD and come (blog post) back to the NYPD! sci-fi movies ...but there's no explanation as to how. Screw it, Samuel L Jackson is in this film! Also explosions, and Scar.
Source: Die Hard with a Vengeance Movie Review science fiction movie - Decker Shado