During the airline sketch, during a more serious moment with Carol and Harvey, Lucy starts to smile, about to break character, but quickly regains her composure.
When Lucy catches Harvey's spat-out cigar in mid-air, Korman gives her a long, admiring glance as if to say "Well done!" Gary Morton's laugh from the audience can be heard during this moment.
When Korman's hijacker loudly announces he's got a gun and is hijacking the plane to Cuba, the other passengers (background actors) don't react at all.