Trivia: There was a false page in the original script in order to fool all of the people working on the film. This was to keep it secret that Darth Vader was Luke's father. Only George Lucas, the producers and James Earl Jones knew the truth. Mark Hamill was told just moments before filming this scene so his reaction would be right, while David Prowse read the lines from the original script "Obi-Wan killed your father."
Continuity mistake: During the battle of Hoth, Wedge flies a full circle around the AT-AT walker and when the walker begins to fall, you can see the cable around its legs, but in a side view of the walker falling, the cable is nowhere to be seen.