Ed Cullen's younger brother Andy has figured out that Lois Frazer was responsible for the murder of her husband and that Ed had covered it up. Putting aside family loyalties he informs the authorities and an all-points bulletin is put out for their arrest. The lovers hear it over the radio as they try to flee the city.
Then ... They make a quick U-turn and head for the nearest city exit, the Golden Gate Bridge, seen in the distance. (Click the image to enlarge it).
Then ... Now on Doyle Drive, aka highway 101, they are approaching the bridge toll booths.
... and Now, the bridge is way busier than it was in 1950. The toll booths are just off the picture on the left.
Then ... Uh - oh, the police have beaten them to it and have the bridge closed off.
... and Now, some changes have taken place at the toll booths since then the biggest of which is the absence of toll-collectors, displaced in 2013 by Fastrak sensors and license plate cameras. But there's still a clock mounted in the center.
Then ... The last San Francisco exit, into the Presidio, is right before the toll booths and Cullen takes it to avoid the roadblock. They decide to hide out at Fort Point and he is next seen heading there, turning into Long Avenue from Lincoln Boulevard (map). A sweeping vista of the Marina district and the City beyond catches our eye.
... and Now, one of those piers has been removed otherwise the marina looks as inviting as it always has. The city skyline of course has seen many changes and the tall white tower in the upper left quadrant is the new Eastern Bay Bridge structure.
... in 1947 ... coincidentally, or not, the same location was filmed three years earlier when Lauren Bacall drove Humphrey Bogart to her apartment in the movie Dark Passage.
Then ... Long Avenue runs into Marine Drive which in turn dead-ends at Fort Point. The camera pans from left to right, following them along Marine Drive. (Click the image to enlarge it).
... in 1957 ... Alfred Hitchcock must have seen this movie. When Scottie follows Madeleine in Vertigo in the fall of 1957 the director used the identical panorama. Note that the old lighthouse keepers' houses on the right seen in the Then image above and the Vertigo image below are no longer there.
Then ... Cullen reaches his destination, old Fort Point, an army garrison once a proud lonely sentinel but now dwarfed by the towering Golden Gate Bridge.
... and Now, it seems time has stood still here in the 60-plus years since the movie was made.