What I really found extremely hilarious in this movie is the scene where James Cagney drags Mae Clarke—the same lady whose face he smashed a grapefruit into in The Public Enemy—across the room by the hair and kicks her out the door after he spots her in his apartment or hotel suite or something when coming home with a lady one night.
James Cagney seems to get himself set up in Hollywood really well; he writes his own fan mail (that's one to way to get started in Hollywood, if you're as dishonest and clever as Cagney) and falls in love with an actress plus gets married to her at the end of the movie. He meets her one day on the set of a Western—or more specifically, he meets her in her dressing room. (Of course, he's dressed up as an Indian when he meets her. And seeing Cagney in an Indian headdress is nothing spectacular.)
And for some reason, in the middle of the movie, Cagney gets a mustache. As it seems to me, he gives the impression of being different with a mustache, not to mention looks different and silly . He looks better without it. I mean, Cagney just isn't Cagney with that silly, curious little piece of facial hair on his upper lip. What's interesting is that he later wears the mustache in movies like He Was Her Man (1934), Ceiling Zero (1936), and Torrid Zone (1940), but only as an act of rebellion against Warner Bros. That's our Jimmy!
I didn't really watch the car chase near the end of the film because I thought it was a little dramatic. And there's a scene other than the hair-pulling-and-dragging that I find funny: it's the scene where Cagney is acting in scene for a movie with his love interest. He's dressed up as a ridiculous-looking Italian and eats pieces of garlic to simulate bad breath. And of course, his co-star is humorously overwhelmed by his breath—and then she pushes him into the nearby fountain, which is hilarious but he laughs about it, so we're laughing with him, not at him.