Blood Sweat & Circuits Continuity Error

Then there is a continuity issue in the cafeteria scene where Mrs Berg is trying to get to grips with the computer manual. Mrs Berg is alone reading the manual out loud and there is an extra in a blue shirt and brown waistcoat sat at the same table. Miss Sherwood arrives and starts to talk to Mrs Berg and the extra gets up to leave. However in the next shot we have a close up of Mrs Berg and the extra is still sat down and then gets up to leave again.