Visible crew/equipment: When Xander and Yelena are in the restaurant and they are shown through the window from outside you can see the reflection of a film crew member in the window.
Revealing mistake: Xander has a XXX tattoo on the back of his neck. There are several scenes where you get a clear shot of the back of the stunt double's neck and there's no tattoo at all. Most noticeably in the scenes during the attack on the cocaine farm.
In the deleted scene of the plane ride on the DVD, when they are going towards the back where Xander is sitting; if you listen, the movie that is playing is The Fast and the Furious, which Vin Diesel also starred in.