The Kipper and the Corpse (a.k.a. Death) - S2-E4
Visible crew/equipment: When Polly is on the phone with the undertaker and she says "I'm afraid somebody's died tonight", the boom mike is visible to the right of the screen.
Gourmet Night (a.k.a. Gourmet's Paradise) - S1-E5
Visible crew/equipment: At the end, the stage lights can be seen in the silver lid. (00:29:00)
Visible crew/equipment: When Virginia shows the cakes she's brought with her the boom mike is visible above them.
The Builders - S1-E2
Visible crew/equipment: When Polly passes Basil the stapler, a boom mic can be seen lifting up out of shot in the top left corner of the screen.
The Builders - S1-E2
Visible crew/equipment: When Stubbs says to keep the door closed, a boom shadow is seen on the wall by the door. (00:27:20)
Visible crew/equipment: Basil runs out of the kitchen and stops Doctor Abbott and starts talking to him. The shadow of a boom mic appears on the wall to the right of the screen twice as he talks to him. (00:15:25)
The Builders - S1-E2
Visible crew/equipment: When the Major says "He lost it you know" to Polly before entering the dining room, the silhouette of a boom mic can be seen on the top right hand of shot. (00:25:20)
The Kipper and the Corpse (a.k.a. Death) - S2-E4
Visible crew/equipment: When Basil, Manuel and Sybil enter the office and find Miss Tibbs fainted next to the corpse, the boom mic appears on the righthand side of the screen next to the fan on the wall. And when the camera switches back to the full shot of all the characters, the boom mic appears again.
Visible crew/equipment: When Basil enters the "Private" room, the camera is reflected on the glass door pane.
Suggested correction: This is way too vague to be accurate. The office (which has private on both doors) is visited by Basil on innumerable occasions throughout this episode and so needs to be more precise.
The Kipper and the Corpse (a.k.a. Death) - S2-E4
Visible crew/equipment: When Dr. Price asks who found the dead guest the boom mike is visible above him.