The Doctor Who season finale is a tricky affair. Loose ends should be tied up, the Doctor’s resolve should be tested thoroughly, and it’s fair to note that his/her companions often have their faith in their extra-terrestrial chum tested pretty strongly, too.

“The Battle of Ranskoor Av Kolos” delivers on all fronts for Season 11’s grand finale, although in the case of Graham, Yaz and Ryan, it’s their faith in themselves that is shaken, and in the case of Graham, the Doctor’s faith in him.

Here are a few things to keep an eye out for, the next time you watch.

1. We normally make quite a fuss about the British comedy legends who’ve made appearances in Doctor Who, and Mark Addy — who plays Paltraki — is certainly one of them. But here’s a thing. Did you know one of his earliest TV appearances was actually in the U.S. sitcom Married… with Children? In 1992 the show set a story in England, and Addy is one of the uncredited characters in the village of Lower Uncton. This was five years before The Full Monty made his name on both sides of the Atlantic.

2. The Doctor says she loves ”wellies.” For non-British viewers, it’s probably useful to note this is UK terminology for waterproof rubber boots, or galoshes. The name comes from Arthur Wellesley, 1^st Duke of Wellington, who designed, wore and made popular a particular cut of leather boot — styled after Hessian military riding boots — in the early 19^th century.

The fashionable fops of British aristocracy — including Beau Brummel — followed his lead, naming their new practical footwear “Wellingtons.” Hiram Hutchinson and Charles Goodyear seized upon the affectionate name when they build their waterproof rubber boot for farm workers in the 1850s.

3. Oh and while we’re on it, Wellington is one of four British Prime Ministers to have lent their name to a practical item. The Eden hat was named after Sir Anthony Eden, the Gladstone bag was named after William Gladstone, and of course there are Churchill cigars.

4. Percelle Ascott, who plays Delph, has appeared in Doctor Who, and he has appeared in stories written by Russell T Davies — but not at the same time. His first major brush with fame came in 2012 when he took the part of Benny Sherwood in the show Wizard vs. Aliens, which was co-created by Phil Ford and Russell T Davies.

5. We don’t often see the Doctor summoning the TARDIS using her sonic screwdriver, and in the outer reaches of Doctor Who media, this issue has been addressed. The comic A New Beginning has Thirteen explaining that this is a “demeaning” way to summon her ship. Demeaning for the TARDIS, that is, who can become “prickly” if it happens too often.

Mind you, for all his bluster about it just being a “scientific instrument” in “The Day of the Doctor,” the War Doctor uses his sonic to summon the TARDIS in several of his audio adventures. Maybe she only gets prickly when Thirteen does it?

6. Fans of finales might be interested to learn that this is the first season ending story since Doctor Who’s relaunch not to feature any scenes set on Earth, or any of the show’s most established villains.

7. To save you going over the season finales in your head to check for monsters, the tally goes like this:

Season 1 – “The Parting of the Ways” – The Daleks

Season 2 – “Doomsday” – The Daleks, the Cybermen

Season 3 – “Last of the Time Lords” – The Master

Season 4 – “Journey’s End” – The Daleks, Davros

Season 5 – “The Big Bang” – The Daleks

Season 6 – “The Wedding of River Song” – The Silence

Season 7 – “The Name of the Doctor” -  The Great Intelligence

Season 8 – “Death in Heaven” – Missy, the Cybermen

Season 9 – “Hell Bent” – The Time Lords

Season 10 – “The Doctor Falls” – The Cybermen

8. This isn’t the first Doctor Who story that features an innocent but powerful person being trapped and their powers used for evil. In “Castrovalva,” the Master imprisoned the Fifth Doctor’s companion Adric and created Castrovalva using the power of his mind. And arguably this is similar to the treatment meted out to the Star Whales in “The Beast Below.”

9. “Yippee ki yay robots” is either a) a genius piece of writing in which Chris Chibnall puts a slightly odd reference to Bruce Willis’s most widely quoted line from the Die Hard franchise into Graham’s mouth because that is the sort of clunky thing a man of his age would say, or b) a slightly odd Die Hard reference in which the word “robots” has to do a lot of work to cover the original line’s four syllable curse word. Let’s just say it works better if it’s a).

10. In honor of Phyllis Logan’s stellar turn as Andinio, and bearing in mind her international fame playing Elsie Hughes in Downton Abbey, let’s round this off with a quick roundup of all the Downton cast who have made appearances alongside the Doctor over the years.

• Hugh Bonneville, who plays Robert Crawley, appeared as the pirate Henry Avery in “The Curse of the Black Spot”
• Siobhan Finneran (Downton’s Sarah O’Brien) played Becka Savage in “The Witchfinders”
• Daisy Lewis (Sarah Bunting) played Javit in “Gridlock”
• MyAnna Buring (Edna Braithwaite) played Scooti Manista in “The Impossible Planet” (2006)
• And among the Big Finish audio cast, we find Jim Carter (Carson), Dan Stevens (Matthew Crawley), Claire Calbraith (Jane Moorsum), Raquel Cassidy (Phyllis Baxter) and Samantha Bond (Rosamund Painswick).
• Samantha also appeared as Mrs Wormwood in the The Sarah Jane Adventures stories “Invasion of the Bane” and “Enemy of the Bane”

And of course Penelope Wilton, who plays Isobel Crawley, was prime minister Harriet Jones. But you know who she is.

What's your favorite moment from the Season 11 finale?