During the episode, Angel says, "I'm not getting trapped at the bottom of the sea," and Spike says, "I'm not getting experimented on by his (the American) government." In The Initiative (1999), the Initiative places an anti-human aggression chip in Spike's brain, and in Tomorrow (2002), Connor traps Angel in a box and sinks him in the Pacific Ocean.
While in the submarine during 1943, Angel and Spike uncover a German document that describes research on how to control demons by using brain implants. Years later, Spike will be captured and implanted with a government chip, rendering him unable to harm humans.
The mentioned "Demon Research Initiative" is likely a precursor to The Initiative. Contrary to Lawson's insistence, a significant portion of the Initiative's work eventually involves capturing vampires and demons and experimenting on them, attempting to develop a race of super-soldiers to use as military tools. When Spike is captured by the Initiative in The Initiative (1999), he asks a fellow prisoner the identity of the captors who mean to conduct experiments on them, specifically guessing that either "the government" or "the Nazis" are involved.
This is the second time in the franchise that Rasputin was implied to have been a vampire. The first was in Checkpoint (2001).
Camden Toy, who plays the Prince of Lies, previously appeared in Buffy the Vampire Slayer (1997) on several occasions. He portrayed one of the Gentlemen in Hush (1999) and the flesh-eating demon Gnarl in Same Time, Same Place (2002). He also had a recurring role throughout season seven as the "Ubervamp."