During filming, one of the aliens' heads fell off its puppet.
Unlike the series and previous specials, which mainly used cartoon animation (although there were some 3D backgrounds), this special has a lot more CGI effects and uses no 2D animation.
This is the third TV special of the franchise after "Why Do We Call It Christmas? (2010)" and "Clive & Ian's Wonder-Blimp Of Knowledge (2012)".
This is the first time in the franchise where character's legs are shown while they are actually walking. prior to this, the puppet's legs were only shown when they were sitting or standing and would walk when their legs were off-screen.