To spice things up and keep Tom Hardy on his toes, director Steven Knight would tell new things to the actors on the phone to incorporate while shooting the scenes. For example, for some takes he told Ruth Wilson, who plays Katrina Locke, to play her character like she wanted to kick Ivan from the house for a while and now she finally had the opportunity.
Locke is a dialog-driven chamber play consisting of one continuous scene. With the exception of Ivan getting into his car at the beginning, a short overhead shot of the motorway midway and a brief pan-out at the end, the entire movie takes place inside Ivan's car.
Whilst driving down the M1 southbound Ivan Locke drives past the junction for Luton Airport (Junction 10), then a few minutes later he drives past the sign for Luton Central (Junction 11). We know that he is driving from the Birmingham area to London. In reality, the Junction for Luton Central comes before the Junction for Luton Airport whilst driving this road. Also, towards the films climax he takes nearly 10 minutes to drive between Junction 6 (North Watford) and Junction 5 (Watford - A41) - in reality this takes about 2 to 3 minutes, even with the 50 mph temporary speed restrictions, and we can see that Ivan Locke is moving at a steady purposeful speed the whole time.
The film follows the journey of Locke towards London from an unspecified location some 90 minutes north of London. However, the construction site at the beginning of the film, and hence at the start of the journey, is actually the Broadgate Circle development in the City of London, also known as 5 Broadgate. This is evidenced by the fact that Liverpool Street station is clearly visible in the background of the wide shot, along with several lesser-known but easily identifiable buildings such as 100 Liverpool Street. Locke's car is initially parked just north of the site, at the corner of Appold Street and Sun Street in London.
Ivan Locke: Well hear this, Gareth. When I left the site just over two hours ago, I had a job, a wife, a home. And now I have none of those things. I have none of those things left. I just have myself and the car that I'm in. And I'm just driving and that's it.