When the thug grabs Shaver by the neck and lifts him off his feet outside the Ho Ho Chop Suey restaurant at about 51:30, there's a thin filament visible over his right shoulder in the close-up shot, probably part of the rig used to actually lift George Segal.
At 01:12:00 when Benson says to trace the call the boom mic dips into the shot.
When Ragulia first arrives and checks into his hotel room, while talking on the phone, a moving shadow of the boom microphone is visible on the wall, upper left of the frame.