Character mistake: S44/E80 Noah Newman works as a bartender, and while at Victor Newman's house says "let's show off some of those drink serving skills." While making a drink he pours straight vodka from the bottle into a martini glass and puts in olives and hands it to Abby to drink. As bartender Noah should know how to make a martini. He doesn't use any vermouth with the vodka and doesn't chill it first by shaking or stirring it before pouring it into the martini glass. (00:11:00)
Character mistake: At Houdini's performance for the Kaiser, a German officer with the rank of Lieutenant Colonel (Oberstleutnant) is asked to assist. Houdini at first correctly addresses him as Lieutenant Colonel, but then incorrectly refers to him as Lieutenant several times after that.
Character mistake: Upon finding the Spanish flu virus missing, Hardison freaks out about it killing 50m people 100 years ago, saying it would be even more deadly today due to the higher population. There's no reason to think so - the death toll in 1918 was massively exacerbated by the aftermath of WWI. Not to mention today we have vaccines, plus most deaths then were actually caused by bacterial pneumonia, which today is easily treated with antibiotics.
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.
Character mistake: In the scene when Dr. Drew has Joey and Eddie on stage, they are arguing and Joey says that Eddie moved away and dumped her twice. Actually, he only dumped her once, when he moved out of his apartment and back home with his parents. The 2nd time that Joey is referring to is when Eddie moved to California for the writing workshop, which SHE helped and encouraged him to do. So he did not dump her 2 times; she basically pushed for him to leave the 2nd time, yet she acts as though this situation never occurred.