When Gustav von Wangenheim (Eddie Izzard), the actor playing Hutter, meets Orlok for the first time. The scene plays out extremely creepy. Bonus points for the fact that the same scene in Nosferatu is just as creepy even now.
Wolfgang, the cameraman, slowly becomes more and more unhinged after first encountering Schreck for the first time, collapsing soon after, becoming pale and sweaty and losing concentration more and more.
During the "dinner scene" where Gustav/Hutter cuts himself, Murnau tricks him into actually cutting himself, which leads to Schreck/Nosferatu trying feed on him. When the lights break down, the crew finally get them back up, only to find Schreck feeding on Wolfgang. The fact that Schreck doesn't bother to attack Wolf while they're alone is terrifying, despite there being multiple people on the set who could stop him. Wolfgang is so near death that Murnau must get a new cameraman (though he is more worried about the movie than his injured cameraman).
Greta realizes that Orlok is a real vampire when she casts a quick glance at a mirror to see that Orlok has no reflection. She becomes hysterical and is forcibly restrained by the crew as they inject her with laudanum so Orlok can feed on her. Orlok feeds on Greta until dawn, killing her, as Murnau watches on and works the camera, caring only for the scene and not the actress. Murnau has just captured her death throes on camera and turned his production into a Snuff Film.
