In the scene where Sully replaces Mike with Randall's henchman in the scream extractor, Randall comes back in the room and says "Where is he? WHERE's LEBOWSKI?" instead of Wizowski.
I listened to it several times and that's definitely what he says.
Sorry, what was the question again? I thought I glimpsed the determined visage of a bloodthirsty and long-dead tyrant. Threw me off.
shareANYWAY... I listened to a digital recording of that bit over and over. Because of background sound effects it's hard to distinguish the first syllable ('Luh' or 'Wa'), but I'm definitely picking up a trace Z-sound instead of a firm B at the 2nd syllable. (That would be a nifty "Easter egg" to hide there, but I don't think they did that.)
We'd have to ask Steve Buscemi himself. (Who had a major role in The Big Lebowski, hmmm..)