Visible crew/equipment: In the scene when Mahone is trying to escape from the restricted area, Sarah looks into the window of the door to see him. The camera moves in as well and you can see it reflected in the glass.
Audio problem: When Gretchen kills the guy in the prison he lets out a very obvious fake scream similar to a Wilhelm scream. Also, he is being choked around the neck, how is he able to make the scream? Take note of when you see this scene in the next episode's review. The guy doesn't make the scream in that version.
The Legend - S4-E10
Audio problem: When Mahone is speaking to Baker, just after Michael goes under the X-Ray, Baker says ' My goal is to build one city that entirely self sustains'. After this, Baker's words do not match the actor's mouth, from the shot behind him; 'Depending on no outside resources'. (00:19:45)
Continuity mistake: At the car dealer where Don Self speaks to the seller, the seller says "How did you find me?" and they are inside the car dealership. Don responds with "I've never lost you". Suddenly when Don answers they are outside the building, like they teleported. (00:13:25)
Answer: Don Self actually worked with Whistler before he died. And Whistler with the bird book actually knew where Scylla was.