Reality, or Fantasy?

Given that we now understand that the conversations Marion hears in her head are illusory, there is a distinct possibility that, as with Scottie in Vertigo, the films proceedings from a highly emotional crossroads (such as Marion being discovered leaving town by Lowery, her boss) are pure fantasy. This fantasy is Marion's visual premonition as to what her fate from that moment on would be.

No time is given as to when Marion left the office or started her journey. She did however, make a trip home and change clothes. Assuming that Lowery spot's Marion on his way to the bar, what is the real possibility that she (who could have spent a considerable amount of time at home) would have run into Cassidy and Lowery who planned on going out for a drink earlier in the afternoon? This run-in could very well be the beginning of Marion's phallic hallucinations. The prelude cue also reemerges at this point, bringing its psychotic implications with it.

The police officer who woke her on the road side appears at the dealership...

Marion, having spotted him, frequently checks his position across the street.

Her nervous demeanor does draw suspicious glances from Charlie, but it is ambiguous whether or not he sees what she does.

Marion looks toward the officer who followed her to the dealership. She's trailed by Charlie, who wont look that direction until a second car pulls into view.

Is California Charlie looking at the police officer, or just the repair man pulling in with Marion's luggage?

Even here, only frames before the cross-dissolve into Marion's continued flight toward Sam, neither Charlie nor the repair man gives notice to the officer.