In the last song, "Nothing's Gonna Stop Us Now," Darla inadvertently makes their performance big AND loud—exactly what she was preaching to Danny a few scenes ago.
As pointed out multiple times, this film is a great big metaphor for the hard times minorities faced when trying to get into film. This makes you wonder how minorities are treated in this universe. Then at the film premiere at the end, you can see plenty of black audience members. They're not being forced to sit in separate seats; they're sitting right alongside the white audience members with no trouble whatsoever. It's possible in this universe, the humans, being forced to live alongside anthropomorphic animals that are radically different from them, were able to get over their prejudice against their own species pretty quickly.
If the film takes place in 1939, how did the animals live long enough to star in (at the time) recent movies like Grumpy Old Men and Twister? Especially Cranston, Francis and Wooly, who are already pretty far along in years.