DCS Barlow's blue shirt inadvertently picks up elements of the Chromakey/CSO blue-screen street footage seen through the laundrette window.
40:56 - DS Watt is briefly superimposed over the youths exiting the café.
When DI Hawkins responds to DCS Barlow's call, no blue background is keyed in behind him, doubtless because of his blue shirt which would also pick up the superimposition.
31:03 - the boom mic is hurriedly pulled out of shot at top tight of the shot; the CSO also vanishes immediately prior of the shot change.