Eric Idle did not receive an Oscar nomination for portraying Berthold/Desmond in The Adventures of Baron Munchausen.
In a way Idle plays almost a third character as we jump to another adventure with the Baron where he finds an elderly Desmond as a prisoner on the moon. Idle continues to be very funny in portraying the initial confused anger at the Baron, since the Baron essentially left him to rot, to immediately accepting when the Baron just owns what he's done. Idle's timing is perfection along with Neville through his hilarious approach in showing that perhaps Desmond is a little lost if not following the Baron's lead in some way. Once he joins the Baron Idle in a way becomes the representative of the old crew of the Baron, who they slowly regain throughout. This in part as Idle just seems most in tune with the absurd comedic tone of the film. Although afterwards isn't always the focus he still makes an impact through his presence. Whether that is when he is given the chance a getting a focus, such as his run as an older man where Idle is all the more hilarious in his physical performance particularly his sheer overwhelming exasperation at the end of it, or just through reacts to the craziness around. Idle nicely adds to the film whenever he can just through his own amusing reactions to what he sees, or again just revealing the age of the older Desmond in portraying the man getting used up by the end of the adventure. It is a fun performance. I wouldn't quite say he quite makes that next step as comedic performance goes, like say Michael Palin in A Fish Called Wanda, this very same year who really is the most talented of the Python group as an actor. Unlike that performance still feels perhaps a bit of a sketch performance, but a very entertaining performance from sketch. Idle never quite embodies fully a character, but rather is just fun to watch being funny Eric Idle, which is really enough.