Regarding mythical animals not getting on the ark.
1. There is a 2 second clip of Unicorns, etc huddling in the rain in the Donald Duck / Noah segment of Disney's FANTASIA 2000.
2. The Richard Rodgers - Martin Charnin - Peter Stone 1970 musical TWO BY TWO includes a "Gitka" who has to be left behind because his mate can't be found in time. This is after the Irish Rovers song, but TWO BY TWO was based on the Clifford Odets play THE FLOWERING PEACH, which iirc is from about 1954, and is presumably a source for the Gitka.