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".
Other mistake: When Elena is taken, Bonnie asks Jeremy for help. She says she needs his blood to cast a location spell to find Elena. But it doesn't make sense. Earlier it was revealed that Elena is adopted, so she and Jeremy don't share the same bloodline and cast could not work well.
Suggested correction: Elena was adopted by her uncle. Grayson Gilbert (her adoptive father) is John Gilbert's (her biological father) brother. Jeremy (Grayson's son) is actually her cousin, and related by blood.
Masquerade - S2-E7
Plot hole: Why did Stefan and Damon suddenly decide to abandon their plans to kill Katherine when the spell linking her to Elena were broken? When only moments earlier, Damon said "The second the spell is lifted, I'm gonna drive a stake right through your heart." So that begs the question why did he never follow through? Why instead place her in the spelled tomb that you know can be dispelled? It makes absolutely no sense when you think about it.
Factual error: During the flash back of 1912, one of the characters pulls an American note out for Damon, and it had the date 2016 or 2010 on. (00:13:00)
Suggested correction: That's not the date. The blue number is basically the serial number, not the date. The series date would be in too fine of print to see in the shot of the bill.
Continuity mistake: Giuseppe Salvatore wasn't buried at the family crypt because it hadn't been built yet. But Lily Salvatore was buried at the crypt despite dying before Giuseppe.
Suggested correction: She faked her death.