Character mistake: Nick asks Janette if she's ever turned anyone else into a vampire - an odd question, considering the fact that he already knows she has. He was there when she brought the baroness across in the 18th Century flashback sequence for "If Looks Could Kill." It's even odder that Janette tells him she's never done it, since she knows that Nick knows she has. Apparently, the only one not in the know here was the scriptwriter.
From Agnes - With Love - S5-E20
Character mistake: Using a Texas Instruments TI-89 Titanium, the seventeenth root of 9,000,355,126,606 is 5.781163783, which means the first prime number greater is seven.
Character mistake: Steffan addresses his brother, Daemon, as "Steffan" at The Grill after Ellina talks to Steffan about the crystal that plagues Bonnie with nightmares about Emily. (00:15:06)
Suggested correction: You missed the point of the scene. They were imitating each other. Stefan was pretending to speak as Damon. Damon replies with "I don't, Damon" and then "you're really hard to imitate".