Visible crew/equipment: The rancor puppeteer's arm can be seen on the far right side of the screen as it starts poking at a hiding Luke. Widescreen version only.
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.
Answer: Yoda. When he was departing for Cloud City to save his friends in the previous film, he promised Yoda that he would return to Dagobah to complete his training.
Phaneron ★
OK. But I thought he was talking about the holeish thing in his hand since he covered it up when he said it. I must have misunderstood it.
The hole in Luke's robotic hand reminds him that he got that robotic hand in the first place because he lost his duel with Darth Vader at Cloud City - a confrontation Yoda warned him he was not ready for.
TonyPH