The 2008 Doctor Who Christmas special, , features several notable production milestones and unique trivia:
: While earlier stories like "The Unquiet Dead" were set in the past, this was the first revived-series Christmas special to take place in a past era (1851 London) rather than the present day. [S0E9] The Next Doctor
: The episode famously features a low-tech Victorian "TARDIS," which stands for T ethered A erial R elease D eveloped I n S tyle—a hot air balloon used by David Morrissey's character. The 2008 Doctor Who Christmas special, , features
: A new monster was introduced—a crude, blocky version of a Cyberman draped in black robes—designed to act as animalistic scouts for the Cybermen. The 2008 Doctor Who Christmas special