Visible crew/equipment: When Karen offers her hand to Jack when they first meet, you can see the boom mike at the top of the shot. (00:37:25)
Visible crew/equipment: When Grace asks Will for his advice on where her mirror in her new apartment should go, she goes running to the wall and when she does, the camera pans over and you can see that the wall stops, revealing it to be a set.
Visible crew/equipment: In the scene where Grace shows Will the new apartment for the first time, you can see the boom microphone pop into the top of the frame several times.
Visible crew/equipment: When Grace is up against the wall pretending to be the ficus a red boom mic drops into shot.
Where There's a Will There's No Way - S1-E7
Visible crew/equipment: When Karen enters the office with clothes and bags, Grace says "Oh Karen, you didn't have to buy me clothes," and above her is the whole boom dipping into view. (01:05:40)
The Truth About Will & Dogs - S1-E10
Visible crew/equipment: Jack and Karen are sitting on the couch, and Grace says, "come on, let's go." There is a boom mic visible at the top of the screen, it rotates towards Grace. (00:14:38)
The Truth About Will & Dogs - S1-E10
Visible crew/equipment: In most of Season One at least (choosing a specific moment here), Will and Grace have a large ornamental silver ball in their living room, which always reflects the studio lights and the fact that there is no fourth wall to the apartment. (00:27:35)
The Truth About Will & Dogs - S1-E10
Visible crew/equipment: When Grace is trying to persuade Will to come out to the cinema with her, the boom mic is visible at the top of the shot. (00:34:35)
Visible crew/equipment: When Will walks through the door, Grace picks up a ball of paper and hits it over to him with a racket. As she does, a boom is visible above her. (01:04:10)
Visible crew/equipment: When Jack is explaining to Will how to visualize someone else while kissing them, you can briefly see a blue mat in the bottom right corner of the screen. This is where Karen later faints. (00:11:55)
Answer: A history of the game can be found at http://www.fast-rewind.com/bacon.htm.
J I Cohen