The mispronunciation of Frankenstein's name as "Frankenschtein" is an allusion to a line from Young Frankenstein (1974).
Rather than don a wig or grow his hair long (which would've taken too long), Daniel Radcliffe wore hair extensions for his role as Igor. Because of this choice, he had to suffer the look and wear them as his own hair throughout filming.
Despite the title, the "twist" that this movie puts on the classic tale is that it is told from the perspective of Igor, Victor Frankenstein's assistant. However, Igor doesn't appear in the original novel "Frankenstein" by Mary Shelley; the hunchbacked assistant originated in the first stage play adaptation of the book in 1823 where he was called "Fritz", an element carried over in the classic movie adaptation Frankenstein (1931). The character was merged over time with a deformed criminal called Igor from several Frankenstein sequels. Lorelei is a unique character; the novel and most adaptations feature an Elizabeth, but she is usually the love interest of Victor, not Igor.
Dunnottar Castle in Aberdeenshire was used as the cliff-top castle location. With Slains Castle, it was visited by Bram Stoker in August 1894 and widely supposed to have inspired the castle of Dracula, the other great creature creation.
The Creature in this film is referred to as Prometheus. The full title of Mary Shelley's original novel was 'Frankenstein: The Modern Prometheus', after the Greek myth of Prometheus, the Titan who created human kind from clay. As such, this epithet was meant to be applied to Victor Frankenstein, not the creature. This is somewhat similar to how the Creature is often referred to as "Frankenstein", whereas "Frankenstein's monster" is the more correct term.