Revealing mistake: When Maddy and Jonathan are driving down to where Jack was found, the scenery outside is constantly repeating itself.
Revealing mistake: Creek reads a newspaper article about Tracy, a missing schoolgirl. The first paragraph of the article is about the schoolgirl, but the rest is about John Major (who had just been ousted by Tony Blair as prime minister when the episode was first aired, but, assuming this was filmed some months earlier, would still have been in power). The first line of the article following the first paragraph starts mid-sentence, as if the first paragraph has simply been pasted over the top of the existing article. This mistake is surprising as there is a photograph of John Major alongside the article and the newspaper remains in shot long enough for it to be spotted without the need to pause the DVD or video.
Revealing mistake: When Jonathan is falling down the stairs when being chased by the ape, there is 1 shot where you can see it's a stunt man. Slow mo may help but is not essential.
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.