I guess none of the casablanca actors got along....

So what if they did not get along ?

It does not matter if actors/actresses don`t get along of screen. The only thing that matter is what happens on screen and that they can pretend to get along on screen if that is what they are suppose to do. 

I mean its no more different than actors who are best friends in real life and hate each other on screen.  Its the relationship on screen that is important not the off screen relationship