The Magician - S3-E4
Revealing mistake: When Oliver meets Thea at the Grind and Jot Cafe (Which looks unsurprisingly like CC Jitters) you can see the cups on the table are from CC Jitters. (00:20:50)
Split Second - S2-E2
Revealing mistake: Shortly after Kiera drives the van past the train tracks, we see a few different shots of Travis and Carlos fighting. In a couple of quick shots, Travis' stunt double can be seen. (00:13:00)