- Acting for Two: Bernard Holley (Axon Man) also provided the Voice of the Eye of Axos, but was uncredited on-screen.
- Creator Backlash: Bob Baker was unhappy at the inclusion of the Master, as he felt that he didn't fit well in the established plot.
- Fake American: Welsh actor Paul Grist as American Bill Filer.
- What Could Have Been:
- Bob Baker and Dave Martin originally pitched this as a seven-part story featuring the Second Doctor. It involved evil aliens who land in Hyde Park in a skull-shaped spacecraft, and featured spaceship battles and even a giant carrot crashing into the park. The production team loved the story, but had it scaled down on account of impracticality and budget.
- The use of Axonite was to have been demonstrated using a rat instead of a toad.
- Scenes cut from the script include a Meet Cute between Jo and Bill and the Brigadier daydreaming of having Chinn taken out the back and shot through the head.
- Working Title: The Gift, The Friendly Invasion, The Axons and The Vampire From Space.
- You Look Familiar:
Trivia / Doctor Who S8 E3 "The Claws of Axos"