As the episode progresses we see Captain Tidwell (Donal Logue) with non-slicked nicely styled hair, then in the scene in the interrogation room we see him with greased slicked hair. This happens at various points on and off throughout the episode.
The establishing shot of the downed plane shows three long straight skid marks. As the two approach the plane the new skid marks meander all down the road, and there's only two lines.
While speaking on the phone to a suspect's daughter, Crews asks her, "Is your mum there?" revealing Damian Lewis's British origins and contrasting with Detective Charlie Crews's American ones.