 This scene was later made into the twelfth "" mobisode, "The Envelope".The exterior of the Hydra was shot in an abandoned theme park, which art director Andrew Murdock thought it fit as a location for the "kind of blocky, 80's-style architecture", where everything was "aged, industrial, and a little bit larger, and a little bit unusual".The opening sequence features Petula Clark's "Downtown", a song that would later be used in another third-season episode featuring Juliet.