Unicorn was originally named "Ingestor" and had a far more organic look to him.
This was Orson Welles last work before his death in 1987. Transformers was released before another film he was involved in called "Someone to Love". However, this film was recorded prior to his voice work for Transformers.
Stan Bush's classic track, "The Touch" was originally written for the Sylvester Stallone movie "Cobra"
Sadly it is understood that Orson Welles actually hated working on the film and later on when he was asked about it, he couldn't remember the name of his character. He even went as far as to describe them film by saying, "I play a big toy who attacks a bunch of smaller toys". The great thing about this is that his voice work being so hate filled for the project actually became rather suited to the character he played.