Shepherd Book doesn't appear in this episode (the explanation given is that he is meditating at an abbey), making it the only episode in the series not to feature all nine protagonists.
The scene in which Malcolm grabs and hugs Kaylee from behind after the hospital robbery is finished was not scripted. It was improvised by Nathan Fillion, because Jewel Staite kept standing in the wrong place during takes.
The futuristic body carriers used to transport Simon and River are actually automotive rooftop cargo boxes made by Thule (the Evolution series) in production at the time of filming.
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 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.