Doctor Who Flux: 14 Best Easter Eggs You Might've Missed
11. The Hopper Virus
It's safe to say that nobody expected The Halloween Apocalypse to contain a reference to Orphan 55, and yet... it does.
When the Doctor boards Karvanista's ship, she empties her pockets and out comes a crisp packet, which contains "leftover Hopper virus particles".
The Hopper virus was first seen in Orphan 55: it infects Ryan Sinclair when he interacts with a vending machine, but the Doctor cures him by luring it into a crisp packet - the exact same crisp packet she pulls from her pocket.
Hey Chris, thanks for reminding us about this trainwreck of an episode!