Roots: Fawlty Towers (Harry Towb's Mario seems to be based on Manuel). Mafioso genre movies, Warlock, Poltergeist ('heading towards the light') and near-death anecdotes as well as (possibly) Altered States. Jung's Synchronicity. Terminator 2 ('I'll be back'). Louisa reads The Mysteries of Udolpho by Ann Radcliffe and may be based on the heroine from Northanger Abbey. Sarah likens N-Space to Hieronymous Bosche's works (probably 'The Garden of Earthly Delights' and perhaps 'The Temptation of Saint Anthony', upon which some of the monsters seem to be based). Uncle Mario mentions 'Tom Tom the Piper's Son', 'Georgie Porgy', 'The Grand Old Duke of York' and 'borrowed' a copy of Jacaranda from a young Brigadier and says 'I put another log on fire' Aladdin the pantomime ('he looks like the Widow Twankie, doesn't he?') Jeremy mentions James Bond twice. Paolo paraphrases the Parable of the Prodigal Son.
Goofs: The Doctor knows Leonardo da Vinci and H.G. Wells, historical figures he doesn't meet until in his fourth and sixth incarnations respectively (see 'Untelevised Adventures').
The sonic screwdriver is the TARDIS door sound [it's on a low resonance setting]; he says it only works on locks [perhaps only at this setting?]
Script pages can be heard turning at several places (whilst Sarah comments on near death experiences, when the Brigadier asks about N-Space, as Mario shows off his blunderbuss, as Guido farewells the Doctor and Sarah, and when the Doctor explains plungbolls.
It is implied that Jeremy has never been in the TARDIS before, although he took at least one trip in it during 'The Paradise of Death'.
Fluffs: 'I'm surprised you can't smell the burning in wh- wh- in wh- wh- where did you say you are?'
'Anyway, in one of these high valleys we came to a r- river that had burst its banks - you c- you could just see the other shore...'
Technobabble: The Doctor constructs a device so he and Sarah to become astral projections, which he ruefully dubs a 'multi-vectored null-dimensional temporal and spatial psychoprobe'. To substitute the effects of Clancy's comet and seal the barrier to N-Space he wires the TARDIS' space-time warping template into its temporal transducers. The Doctor uses anti-plungboll spray.
Double Entendres: 'Is there any possibility that you can come out?'
Mario's indiscreet 'I show you the painted-a-ceiling in my bedroom, eh?'
'No Sarah, don't take anything off - that'd ruin everything'
'Come, I'll show you the last of my secrets'
Fashion Victims: 'I feel like a refugee from Pride and Prejudice' says Sarah, in period costume.
Dialogue Disasters: 'Never mind the piccolo diablo...'
'Slam-o bam-o thankyou Ma'am-o'
'Do ya tink I did it by... letting myself get kicked around by some two-bit godfadda wid cowshit between his toes?'
'I come-a to give you a piece of toast'
'One, two, three heeaaaavvveee...'
'Oh I say, he's vapourised the goat.'
Dialogue Triumphs: 'If you want to know the time, ask a Time Lord.'
Continuity: N-Space or Null-Space is another universe separate from ours, where every living creature from our universe has an alternate form, or N-form. Upon the death of an individual their dead N-form leaves N-Space to a higher plane, rather like travelling up a tunnel of light. Their negative emotions are left behind to become monstrous beings. Occasionally, after trauma or when an individual cannot accept their own death, this N-form remains in torment, and thus N-Space is the home of much evil and suffering. N-forms desire souls for sustenance and may escape through flaws in the N-Space barrier into our universe, where they relive out the last moments of their life as a ghost. Poltergeist activity is common in the presence of an adolescent (see: 'Winter for the Adept' for comparisons), though the Doctor dismisses poltergeists as a form of low grade N-form.
The Doctor's apparatus is made up from many things, including the skull of a rat and a six-minute egg (which has a surprisingly high psychic capacity, apparently). Using an 'OB (Out of Body) dimensional transducer' and 'psychoprobe', he and Sarah are able to assume astral form and travel backwards and forwards in time. Whilst doing so they remain visible as spectral forms, not unlike ghosts. They are able to carry physical objects.
The Brigadier has a 92 year old Italian great uncle called Mario who considers him his closest heir. In fact, Mario is a second cousin to the Brig's Granny McDougal (he reasons that as she was only half-Italian that makes him 1/8th Italian and 7/8ths Scottish). He tells the Doctor he doesn't believe in ghosts.
As in 'Silver Nemesis', magic works. There appears to have once been an elixir of immortality which allows Vilmio to live for over 300 years. The Doctor theorises that its formula is 'a Latin translation of a Spanish version of an Arabian extract from a Greek alchemic text taken from an Egyptian esoteric original of immense power... the Babylonians probably had a hand in it too.' During his bargaining with Vilmio the Doctor mentions other 'Lords of the Galaxy', though he may have been bluffing. Clancy's comet, or 'the wing of the dragon' passes Earth every 157 years (1504, 1661, 1818, 1975 [but see Location].
Sarah hasn't had any luck in persuading her editor Clarinda (see 'The Paradise of Death') to print her stories of time travel and alien worlds. Instead, she has periodically retired from journalism to write the Great British Novel. Her uncle Hubert has or had a grandfather clock.
Jeremy has taken her with him on holiday, his mother having bailed out at the last minute. He is a pretty good shot with a rifle, having had practice at the fairground (the last time he won a plaster Venue de Milo, a 'silver' jug and a pink teddy bear). He went to boarding school and has an Uncle Teddy who shoots. He knows goats.
At the beginning of the story the Doctor cooks himself Welsh Rarebit. Plungbolls are small furry creatures about the size of a thumbnail, native to Gallifrey. They live in the snow in the planet's mountains and attach themselves to any source of warmth (thousands can cover a man). Anti-plungboll spray makes them drop off, squeaking. The Doctor once walked the mountains of Gallifrey with his 'teacher' (judging by his anecdote to Sarah and the fact that the teacher lived outside of the Capitol it may have been the hermit - see 'The Time Monster'). He says pasta-styled dishes pop up all over the galaxy, 'but spaghetti is the best'. He postulates that Hieronymous Bosch may have once visited N-Space, possibly aided by Maximillian. Scratchin is a game on Gallifrey. This is the second Doctor Who story which mentions Elvis (see: 'Time and the Rani')
Links: The Doctor brings back a modified stun gun from Parakon (The Paradise of Death). He lapses into deep meditation to remove his 'self' from mental conflict momentarily. To comfort the grieving Sarah the Doctor tells her a story of the hermit he once knew (The Time Monster). Winter for the Adept
Location: San Stefano Minore, near Sicily around the 18-22nd May 1972 [as noted in Continuity above, the comet was actually due in 1975, however in order to remain consistent and preserve the UNIT era dating cycle used in the original Discontinuity Guide, we have taken 1972 as the present day year. We can explain this anomaly by saying the 157 years between appearances of the comet is only a rough estimation.], 1818 and shortly after the taking of Grenada in 1492, circa 1504.
Untelevised Adventures: The Doctor refers to 'Bertie' (presumably H G Wells, c.f. 'Timelash') who once borrowed his ion focusing coil for an invisibility experiment. He has a lock of Sarah Siddon's hair. Horace Walpole is an old friend. Leonardo [da Vinci] is an acquaintance (which contradicts 'The Masque of Mandarogora' and 'City of Death').
The Bottom Line: 'Young man, an awful lot of nonsense is spoken by people about the Fourth Dimension - and the Fifth and the Sixth, and the rest for that matter.'
After overseeing a finale based on Buddhism, it seems odd that Lett's last contribution to the third Doctor's era is something of a Catholic model of the afterlife, with a realised Purgatory in N-Space and Stephen Thorne once more playing the Devil in all but name. Still, it's something of an improvement on 'The Paradise of Death' - there are too many silly accents, but Jeremy is less irritating. Neither disastrous and far from a triumph, nor entirely in keeping with the era it tries to evoke, 'Ghosts' is just... odd.