On YouTube - Glimpses of THANK YOUR LUCKY STARS (David Butler, USA, 1943) especially Errol Flynn singing and dancing

Thank Your Lucky Stars was made by Warner Bros as a WW2 fundraiser, with a slim plot involving two theatre producers played by Edward Everett Horton and S Z Sakall. The stars donated their salaries to the Hollywood Canteen founded by John Garfield and Bette Davis who appear in this film. The female who gets most attention is Dinah Shore who does four utterly anodyne numbers of forgettable songs.

The writing is credited to Norman Panama and Melvin Frank, later the authors of the comic masterpiece The Court Jester. They give Eddie Cantor far more and far better jokes than he deserves. Needless to say it's a film that has its moments. 

The numbers were written by Arthur Schwartz and Frank Loesser and one of them, sung in the film by Bette Davis, "They're Either Too Young or Too Old" was nominated for an Oscar, but lost. The best number features a slim and skinny legged Errol Flynn singing and dancing to a stage number set in an English tavern. Flynn enters and cadges drinks while singing and launches into "That's What You Jolly Well Get,''. His Australian accent occasionally pokes through.

And here's the Bette Davis number.

It appears that Warners has done a 4K restoration of the whole 2hour 7 minute show which you can find when you hunt round the channels