Plot hole: Why on earth would a sleazeball like Adam Klaus be worried about news of a one-night stand being revealed? He'd welcome the publicity, if anything. Anyone threatening to go to the papers with news of a bit of rumpy-pumpy with him would be wasting their time.
Continuity mistake: When Le Fley runs through the house to be shown that the painting is missing, he is seen in three shots; in the first he is barefoot, in the second he appears to be wearing light-coloured mules, loafers or some other lightweight footwear, and in the third he is barefoot again. It is a little hard to see this in the second shot as his feet are moving quickly, so I could be mistaken, but it does look like he has something on his feet.
Plot hole: How did the guy who stalked Emma Lazarus managed to get the box containing her head on the aeroplane without it being checked by airport security? As airline passengers are required to have their personal belongings on them scanned, this should have been detected by the airport security scanner and security staff would have detained the passenger or even arrested him before he had the chance to board the plane.
Black Canary - S2-E7
Revealing mistake: Creek reads a newspaper article he finds in a scrapbook. The second column of the article repeats a block of text from the first column. (00:52:00)
Chosen answer: It was a bottle of turpentine.
Methylated spirit, always coloured purple.