When Rosita is talking with Sasha about her past, Rosita sheds a tear, but moments later, her cheek is dry.
When Rosita is looking through the rifle scope, the cover is still on.
When the Saviors visit the Hilltop and enter the main house, the extra nearest the camera can be clearly seen looking for his 'mark'. That is, the spot where he is to walk to and stop.
Close to the end of the episode (S7E14, 39 minute mark), Sasha and Rosita are using the rifle scope to get a closer look at Negan's compound. When it cuts back to one of them holding the rifle, you can see that the lens caps are still on the scope. Making it impossible for them to actually see through the scope.