The half-scale helicopter mock-up used for the exteriors of the "flying ambulance" was found by a fan in an aircraft graveyard located outside Mojave, California, still fully painted and reasonably intact. A fan campaign has begun to raise enough money to purchase the prop from the owner and donate it to a museum.
The drug that Simon and River take to slow their physiological functions enough to make them appear to be dead is fictional, but not science fiction; it is a major plot device from William Shakespeare's play Romeo and Juliet, which he wrote in the 1590s.
The E.M.S. vehicle used to sneak everyone into the hospital is a modified version of the Russian Airforce's Mi-24 Hind attack helicopter. The main rotor was removed, however the short wings and twin bubble canopy remained intact. The section that Wash sits in to fly the craft is actually the second half of the canopy; the first was filled in with the rubber material.
Ariel is the name of one of Uranus's moons, which, like all Uranian moons, is named after a character from Shakespeare (in Ariel's case, "The Tempest") or m Alexander Pope's "The Rape of the Lock" (characters named Ariel appear in both works).