I actually really enjoyed that flick....until the end. But I heard that THAT *was* budgetary. Meaning....they did the story line for FOTR and TTT, and suddenly got the ROTK and realized they were out of money, so they had to wrap up the final part of the trilogy in like, ten minutes.
The director himself confirmed that this story is untrue. It was originally supposed to be three films, then it was negotiated down to two films, and then United Artists released the first film as "The Lord of the Rings," instead of "The Lord of the Rings: Part One," as it was supposed to be, and then they refused to fund the sequel.
In order to cover this fact up later on, when the rights went to Time/Warner (who had purchased the catalog of Saul Zaentz, who produced the film), they went and overdubbed the alternate narrative over the film's climatic ending. It originally had the narration
after the ending, and the announcement was that a sequel would come later. But as you know, this didn't work out too well.
And then Rankin/Bass aired their version of "The Return of the King" in May, 1980, and it was too late for them to change their minds. United Artists folded in November, after the box-office bomb "Heaven's Gate."