Cassandra Truth: April tries telling people they are in danger and need to get out during the dance, but they don't take notice of her.
Crazy-Prepared: The Doctor just so happened to have a spare leg for Ram in the TARDIS.
Distracted by the Sexy: Matteusz goes mute at the sight of Ram and Rachel entering the room, causing Charlie to meekly insist he looks nice as well.
Dude, She's A Lesbian: Almost. Tanya is about to say she doesn't think Charlie is interested in girls, but cuts herself off before April can get the message.
Freeze-Frame Bonus: Besides the names of Clara Oswald and Danny Pink, the memorial wall is loaded with names that have been mentioned in various media related to Doctor Who, including novels, and the name of the Doctor's granddaughter, Susan Foreman.
Genre Savvy: The kids, Charlie excepted, are familiar with shows where aliens pose as humans, or where a school is continually threatened by one Monster of the Week after another. So they take these revelations in their stride and go on to ask pertinent followup questions.
High-School Dance: The climax of the episode occurs at the school prom.
Incompatible Orientation: April has a crush on Charlie at first and attempts to ask him out, but is rejected (matter-of-factly, due to his having No Social Skills). He later tells her he'll ask Matteusz, one of their male classmates, to the prom, and she realises he's gay and wasn't just snubbing her.
"Now, will you please let me go to the—(Corakinus stabs her from behind)"
Late-Arrival Spoiler: For anyone not familiar with the fate of the Doctor's previous companion Clara Oswald, her name appears on a board honoring those associated with Coal Hill School that had died or disappeared.
Mutual Kill: The only way to kill a Shadow Kin in this episode. Quill's displacement gun hits both target and shooter, scattering them. When April's shot is knocked off course by Charlie, she and the Shadow King Corakinus are left with the same heart. She threatens to stab her heart at one point, since it would also kill Corakinus.
New Transfer Student: Charlie has recently transferred from "Sheffield", along with Miss Quill.
Nice Guy: Matteusz shows himself to be this when he tells April she can take turns dancing with Charlie and himself so that she isn't the only one at the prom without a dance partner.
Rewatch Bonus: Tanya starts making some remarks about her "white" friends, which hint at a later storyline where she reveals her resentment toward the gang.
Stop, or I Shoot Myself!: A variation. April threatens to stab her heart with a chair leg if Corakinus doesn't leave, as her and Corakinus's hearts are connected and this will kill them both.
Surprisingly Sudden Death: While Rachel is talking to Ram, Corakinus suddenly appears and stabs her in the back.
In the flashback to when the Doctor first rescued Charlie and Miss Quill, Charlie is seen about to open the Cabinet of Souls. The significance of that isn't explained until later: he would have wiped out the Shadow Kin — taking their species with his. The implication is that the Doctor has detected this and has arrived to try and stop him from making a massive mistake.
April threatens to do this to Corakinus.
Title Drop: 'Let's dance! For tonight, we might die!'
