Doctor Who Series 10: 14 Easter Eggs & References You Might've Missed In 'Smile'

3. Bill Watches The Big Bang Theory

When Bill accesses the ship's computer, it plays a high-speed video containing the history of the Earth. All this scene needs is Barenaked Ladies' The History of Everything playing over the top and this scene would be a dead ringer for the opening credits of The Big Bang Theory.

Naturally, this blitz through human history brings up some nods to past Doctor Who adventures. For instance, we get a glimpse of Stone Henge - which appeared in 2010's The Pandorica Opens - and Vincent Van Gogh - who the Doctor befriended in the same year's Vincent and the Doctor. Elsewhere in the episode, Bill espies a bust of Egyptian queen Nefertiti. She travelled with the Doctor in 2012's Dinosaurs on a Spaceship.

Lastly, Bill crying while watching a video of some tragedy happening to Earth in the future is highly reminiscent of - here it is again - The Beast Below. In that episode, the camera shows Amy's sobs as she watches footage of solar flares hitting the planet.