Visible crew/equipment: When the gunman tries to flee in the ambulance Jerry rams the truck into the vehicle to prevent his escape, and when Captain Grover pulls the gunman out of the ambulance, we can see the boom pole/mic's reflection moving on the windshield.
Continuity mistake: After the gunmen exit the gallery hiding amongst the hostages, during the gunfire multiple bullet holes are made on the back doors of the ambulance, but all those bullet holes have vanished a few shots later,.
Chosen answer: They are Junior's SEAL buddies.