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 back to the NYPD! ...but there's no explanation as to (blog post) how. Screw it, Samuel L Jackson is in this (blog post) film! Also explosions, (blog post) and Scar.
Source: Die Hard with a Vengeance Movie Review - Decker Shado