Gilda is just like Casablanca if Casablanca had a happy ending, which would have been a bad idea even if it hadn’t been already done two years earlier in To Have and Have Not (which at least had Bogie in it).
Like Casablanca, Gilda revolves around a love triangle set in a gambling establishment in an exotic location, but while Casablanca takes place in North Africa during World War II, Gilda takes place in South America just after the war. Moreover, if Casablanca ends with "the beginning of a beautiful friendship", Gilda concludes with the continuation of a horrible romance.
Following the Rick Blaine (Humphrey Bogart), Ilsa Lund (Ingrid Bergman), Victor Lazlo (Paul Heinreid) pattern, Johnny Farrell (Glenn Ford) lives a carefree existence running a casino in Buenos Aires until Gilda (Rita Hayworth) walks back into his life hand-in-hand with Ballin Mundson (George Macready).
Macready, despite his character's unfortunate name (Victor Lazlo sounds merely foreign; Ballin Mundson is positively alien), and especially Hayworth, look their parts to a T; as for Ford, let's just say he was taller than Bogie, but there’s a big difference between height and stature.
Gilda has married Ballin after knowing him all of one day. This drives Johnny mad with jealousy; however, to Gilda's chagrin, he’s less jealous of Ballin than of her — and understandably so; casino owner Ballin is something of a mentor and father figure to Johnny, who in turn is his bodyguard, confidante, and right-hand man. In short, Johnny is betrayed by Ballin and Ballin is betrayed by Gilda with Johnny's complicity, though Johnny more to protect Ballin than to help her.
The whole thing is sick and twisted and a lot of fun thanks to Hayworth; Johnny hates her with a passion, and if we never question the authenticity and intensity of this feeling, it is not Ford's performance but hers that makes us, not only believe in Johnny’s hatred of her, but in fact even share it.
Like Bette Davis in Of Human Bondage, Hayworth owes her well-deserved fame to an absolutely infamous character. The difference is that Leslie Howard eventually wins, like Scott Pilgrim, The Power of Self-Respect, Johnny, however, ends up not only putting the pussy on a pedestal, but keeping it there.
He begs Gilda: “I want to go with you … Please take me,” and is lucky, or rather unlucky enough that Gilda welcomes him back with open arms, rationalizing this decision with the dubious logic that “No one has to apologize because we were both scoundrels, right? Isn’t it wonderful?". All things considered, some couples will always have Paris; for others, there’s always Family Court.