Count Dracula dresses in Bela Lugosi's classic vampire costume for the dinner aboard the Demeter.
The character Lord Ruthven (pronounced "Riven") is a reference to a literary vampire that predates even Dracula. The 1819 novel "The Vampyr" by John Polidori featured one of the first vampires in English literature, supposedly based on Lord Byron, and was a product of the same contest between Polidori, Byron and the Shelleys that produced Mary Shelley's Frankenstein. The same character also provided inspiration to Gilbert and Sullivan for their opera "Ruddigore", about a young innocent cursed to become "Sir Ruthven Murgatroyd" and commit a crime a day or die in agony.
The Demeter is cursed by the mystery of what's Inside cabin No. 9 - inspired by the comedy horror TV show Inside No. 9 (2014) by Steve Pemberton and Reece Shearsmith, both alumni of The League of Gentlemen (1999) with Mark Gatiss.
When Dr. Sharma mentions his research into the undead or "Nosferatu", he mentions "there *are* such things". This is a reference to the epilogue speech delivered by Edward Van Sloan, who portrays Van Helsing in the 1931 version of Dracula. It ends with "[...] just pull yourself together, and remember: there *are* such things."
Clive Russell played Sir John Ross on The Terror (2018), another show about a ship lost at sea due to the intervention of an evil supernatural force.