The scenes of Symphony Angel in the desert and the Mysterons attacking Cloudbase presented a number of challenges for Century 21's special effects department, headed by Derek Meddings. A scene in which Symphony looks up as Destiny Angel's fighter flies past her required close collaboration between the puppet operators and the effects crew, the former keeping the puppet under control while the latter moved the scale model across the set. The Mysteron spacecraft were modelled on "flying saucer" UFOs commonly reported during the 1960s. To make the spacecraft appear to spin in the moonlight, Meddings added "veins" to each model to reflect the lighting in the studio. Due to a shortage of model operators on set, the models were flown only in the foreground; flashing light bulbs were fitted to the backdrop to give the impression of a larger fleet.