The conclusion to George Lucas' epic Star Wars saga was, famously, originally called something else, and there are promotional materials to prove it.
The final story for what would eventually become Return of the Jedi was actually constructed rather late in the film's production, so even as preproduction was well under way, the Star Wars team weren't quite sure what they were getting into at times. According to screenwriter Lawrence Kasdan, Lucas actually picked Return of the Jedi as his first title choice, but Kasdan argued against it, so Lucas went with Revenge of the Jedi instead, and that title stuck throughout production, right up until it was time to release posters and a teaser trailer. Several thousand posters for Revenge of the Jedi were released, but Lucas stopped shipping them to theaters when he decided the title should be different, and if you can find one in good condition now, you stand to make a few hundred bucks.
The Revenge teaser trailer, though, is now easier to find thanks to the official Star Wars YouTube channel, which just posted it more than 30 years after the film was originally released. The trailer features all the Return of the Jedi elements you remember, including the Sarlacc pit, the AT-ST walkers and the Millennium Falcon racing through the innards of the Death Star, but it also features a couple of interesting Revenge of the Jedi oddities you didn't see in the final film. For one thing, you'll notice that Luke Skywalker's lightsaber is blue, not green. For another, you'll see a shot in which Alec Guinness' Obi-Wan Kenobi looks very much alive, and not at all like a Force ghost. The YouTube description says this was simply a shot before "spirit" effects were added, but it's worth noting that Lucas' original plan was to bring Obi-Wan back from the dead, and not simply include him as a spirit.
Check out the teaser above.