Visible crew/equipment: (Widescreen Only) The rancor puppeteer's arm can be seen on the far right side of the screen as it starts poking at a hiding Luke.
Suggested correction: Just loaded that scene up on Disney Plus. The rancor's puppeteer's arm is actually not visible. The rancor is actually an animatronic.
According to Wookiepedia, the Rancor was a puppet, not an animatronic (a man in a suit was tried, though). For the digital releases, it was recomposited, so the visible arm was probably removed.
Visible crew/equipment: After Luke cuts Vader's hand, there's a shot of the Emperor walking downstairs. The shadow of the crew is visible on the lower left corner of the image. It can't be the shadow of Luke.
Visible crew/equipment: When C-3PO And R2-D2 come up to Jabba's palace in the beginning of the movie, in the close-up, you see overhead stagelights in the reflection of C-3PO's head.
Visible crew/equipment: During the speederbike chase, there are several shots where the support arms holding up the fronts of the bikes are visible.
Visible crew/equipment: During Luke's conversation with Ben's ghost, you can see a boom microphone in the background. This applies to the original wide-screen version.