At last! Doctor Who is finally back on our screens for the first full season since 2015. We have had a couple of enjoyable if frothy specials in the meantime, but now the show is back to entertain us week after week for the next twelve Saturdays.
In contrast to most Doctor Who season openers, The Pilot was a bit of a slow-burner, as it focussed on introducing Bill's character to the audience and the Doctor's world as a whole. The plot might have been slight - something about a sentient alien puddle - but the character work was very strong.
In the area of callbacks and nods to the past, however, The Pilot was jam-packed. There are some broad references that casual fans can pick up on - a few familiar faces or items here and there - but also some pretty obscure ones - borrowed quotes, props or even sound effects - that are much harder to spot.
You can't have missed the tongue-in-cheek title of this episode. The eponymous Pilot is ostensibly Heather, who is chosen by the alien puddle to take it across the universe, but the title is obviously also referring to the fact that this opener serves as a fresh start for the show. Fittingly, then, the episode features a couple of nods to the previous pilots Doctor Who has had over the years.
Firstly, there is a reference - that I will elaborate on in a moment - to the Doctor's granddaughter Susan, who first appeared along with the Doctor in Doctor Who's first ever episode The Unearthly Child in 1963.
The Doctor later describes the TARDIS' chameleon circuit to Bill as "a cloaking device." The last time he used this term - originally coined by Star Trek - was in 1996's Doctor Who: The Movie. This UK/US co-production starring Paul McGann was a backdoor pilot for a new series that never materialised.
Finally, Bill's alarm clock has the exact same sound effect as Rose's in 2005's Rose, the episode that functioned as the pilot of the modern series. On both occasions, the companion waking up upon hearing the sound is the first thing we see after the opening credits.