- Accidentally Correct Writing: When Ian and Barbara are discussing Susan's mysteriousness, Barbara remarks on how Susan did not know how many shillings were in a pound, and Susan's excuse was that she forgot that "the decimal system hadn't started yet." The United Kingdom did eventually switch to a system of 100 pennies to a pound in 1970.
- Actor-Inspired Element: According to the DVD info text, the striped top Susan wears in this and later stories belonged to Carole Ann Ford and was part of an alternate costume she suggested for the character after it was decided to abandon the more adult, futuristic look of the unaired pilot. According to the commentary, Ford's suggested outfit also included black leggings and boots, which were rejected as too sexy, so jeans were worn instead. Ford would wear the same striped top in The Great St Trinians Train Robbery.
- The Cast Showoff: Carol Ann Ford was a trained dancer, which is exploited in her Establishing Character Moment of her doing a very peculiar dance to some chart pop music.
- First Appearance: Of the Doctor (duh), Susan Foreman, Ian Chesterton and Barbara Wright. Also, the TARDIS.
- Rerun: This episode was rebroadcast a week later. The reason for this was due to the double whammy of a major blackout across a good swathe of the United Kingdom, and many people not tuning in, instead listening to news of US President John F. Kennedy's assassination which had happened the previous day. In fact, the first broadcast of this episode was delayed for 90 seconds to accommodate a late-breaking bulletin about the assassination.
- What Could Have Been:
- The original idea for the first episode saw the Doctor and his companions being shrunk. This concept was reused for "Planet of Giants".
- Ian and Barbara's relationship was much more romantic in the original script.
- The episode originally ended with Ian making fire for the tribe and our heroes leaving peacefully. This was changed to something more action-packed.
- Originally, the part four cliffhanger would have seen the TARDIS materialise near a Frank Lloyd Wright-style house floating in the air. This would have led into The Masters of Luxor, a story that was abandoned and replaced with "The Daleks".
- Working Title: The Tribe of Gum and Nothing at the End of the Lane.
Trivia / Doctor Who S1 E1 "An Unearthly Child"