There are so many little details.
With all the special effects that are used in films today it can be easy to assume that set designers have it easy. And, in some cases they do. But, when it comes to making things looks older many set designers only use the most authentic articles they can get their hands on. This means that when the camera pans over a modern street where filming is taking place, audiences are transported back in time. And, to properly accomplish this you have to know your eras and your materials.
Simply put, most designers for film will actually transform the scene. Instead of relying on some digital magic, they will cover modern signs with old ones, or even use hand-painted ones when shooting on location on a real street. All the cars on the street have to be from the right era, and so do the license plates on those cars, too. Newsstands, shoe shiner stands, and show repair places are other iconic locations from the past, but each one has to be stocked with publications and products from the right month and year.
There are plenty of things that can’t be changed when filming on location, such as parking meters and bike racks. These featured can’t simply be made over. In these cases crates or boxes can be used to hide them. Or, designers can always just drop in a strategically-placed phone booth to hide them away.
The tiniest details have to be accounted for as well, down to the right cereal box or laundry soap in the window of a small grocery. And, to do all this you need a store of old signs, artifacts, products, and other props at your disposal.
See how they turn back time in the video below with set designer, Rena DeAngelo, who created the look for the 2021 film adaptation of West Side Story.