Visible crew/equipment: When Logan and Jenny Agutter meet the shiny robot in his ice lair, you can see the reflection of the film crew many times on the shiny body of the robot. (01:07:00)
Visible crew/equipment: Near the beginning when Logan and his friend come up the escalator, you can see the reflection of the film crew on the mirror behind them. (00:05:04)
Visible crew/equipment: Right after the Carousel segment, a red-clad man is running because his life-gauge says he's 30. He runs through a semi-open corridor that has dark tan bricks. A moment after he passes through the area, and turns back to see Logan aiming at him you can see a spark emitting device has been colored the same as the bricks, but noticeable. It is a special effect to complete the scene.
Answer: In popular American lore, the Sandman is responsible for putting sand over your eyes to make you go to sleep. In this context the "sleep" is a euphemism for death, and the enforcers are responsible for making sure that everyone dies on time.
Phoenix