A lot of people cringe when watching Dumbo these days due to the rather racist depiction of Afro-Americans as crows (crows for jiminy's sake!) in one scene in particular. For me however it is also hard to watch the film without some diminution of enthusiasm on the grounds of what was happening throughout its production to its animators who had dared unionise when Dumbo was in pre-production, over 500 of whom were then to pay for their "crime" with Disney's attempt not just to sack them but destroy their potential careers in Hollywood as animators altogether. The 1941 strike at Disney was one of those watershed moments in labour relations in the States. The Screen Cartoonists Guild emerged so much better organised out of it that its legal staff were suddenly in big demand from other unions in terms of defending themselves against ridiculous smear allegations designed to destroy them ("Bolsheviks" being Disney's own contemptuous dismissal of his staff when they complained about their pay deteriorating as his profits increased). Likewise the big studios followed Disney's lead in purging themselves of potential "troublemakers", thereby establishing the strained and exploitative rules of contractual obligation for Hollywood employees which would eventually lead to the establishment of independent production models as a reaction by those adversely affected - out of which just about anything worthwhile produced by Hollywood emerged afterwards.
If you can bring yourself to watch Dumbo have a look out for the portrayal of Art Babbitt as a Bolshie clown. Babbitt (creator of Goofy) was arguably Disney's most innovative animator and much of Disney's commercial success up to that point rested on his contribution. After the strike he served with distinction in the US Marines and also helped found UPA, the animation company which won many deserved awards in post-war years for its encouragement, adoption and development of new animation techniques (and which also produced many educational shorts for US government contracts - including the defence forces - some of which are still recognised as classics of their type). This didn't stop loveable old Walt appearing before McCarthy during the House Committee on Un-American Activities in the 1950s and denouncing his now competitor Babbitt as a communist infiltrator, an allegation that served to destroy Disney's credibility more than it ever hurt Babbitt.