Editing style –

Casablanca uses continuity editing to provide an easy flow across the narrative, so the audiences can easily progress through the film without questioning the storyline.

Example –

For example In this scene, a master shot is used to establish the presence of Ricks bouncer at the door. Looking towards Rick to check weather they may enter the gambling room. Turning into a medium shot, the desired guests enter and one is held back, checking with rick, the undesired guest is in the same position of ricks eye in the next scene, This shows an eyeline trace as ricks eyeline matches the angle he is facing.