The subway station in the Matrix 3.

The ultimate liminal space that only exists to represent a place that is transitted through, yet is also infinite in space and time if you do not essentially possess the key to actually leave.

I guess arguably, any repeated timeloop type of movie essentially turns most of the world into a defacto liminal space.

But yeah, most literally, a liminal space is a space designed to be moved through, not inhabited.

A doorway or hallway vs a room.

A waiting room at a doctor's office, a queue at an airport.

A highway, bridge, or train tracks, vs wherever they are leading you to.