Obi-Wan lost his eye in a tragic drunken lightsaber-juggling incident.
To create the human figures occupying the miniature of Luke's landspeeder, 98th-level visual effects wizard Lorne Peterson looked for a quick and dirty alternative to actually sculpting wee versions of Luke and Obi-Wan, and he found it in the form of two Steve Austin action figures, which he mildly disguised with tiny Luke and Obi-Wan robes and stuffed into the vehicle. Although it looks downright ludicrous from the front, it totally worked in the film because the prop was shot only from far away or from behind, and for only short durations. Which is a good thing, because miniature Luke isn't wearing any pants.
And Obi-Wan doesn't have any fucking legs.
But in the quest to cut corners, nothing beats this next example.
First, a quick lesson in special effects history: Pre-CGI model makers used a process called kitbashing, wherein they'd plunder store-bought model kits (typically tanks and military aircraft) for high-tech-looking plastic bits, which they'd then glue together into even more high-tech-looking plastic bits to make a good-looking model for the film. But you know what makes this easier? When stores start selling models from your actual franchise.
That's right -- once the original Star Wars became an honest-to-goodness phenomenon, there were tons of Star Wars model kits on the shelf of every single toy store in America that could be easily kitbashed for the sequels. In at least one confirmed case, an entire off-the-shelf X-wing model kit was used for Return Of The Jedi. It's not even really fair to call this a case of kitbashing, because all Lucasfilm did was simply give the model a metal support structure, paint on some grime, and call it special effects genius.
Of course, the real genius was whoever drew Luke's face on that box.
Said X-wing has been positively identified by the hobby community as an off-the-shelf MPC kit by "tells," such as its uniquely gaunt underbelly, the orientation of its laser cannon tips, and probably the words "Made in China" stamped on there somewhere.