Pinocchio (lost Mel Blanc's "Gideon the Cat" dialogue from Disney animated film; 1940)
From The Lost Media Wiki
For Disney's 1940 animated feature Pinocchio, prolific voice actor Mel Blanc had recorded several lines of dialogue for Honest John's sidekick Gideon the Cat. According to one interview, Blanc had given him a drunken sort of voice and Walt Disney had disapproved of it, subsequently deciding that the character should instead be mute.
In the final film, all that remained of Blanc's recordings were three hiccups; it is not currently known if any of the unheard recordings still exist in some form or if the reel was destroyed.