It’s not mentioned anywhere on the DVD, but there’s a bonus audio track which I can only assume is a recitation of the non-dialogue parts of the script, along with notes for visual cues. The narrator for the actual movie speaks English with an American accent, but the narrator on this extra track has a slightly snippy British accent. I’m not sure why, but one motivation could be to distinguish it from the other narrator’s voice.
In terms of the basic script, the narrator says things like, “She picks up her file, briefly looks Tom in the eye, then walks away. Tom is thoroughly confused.” But it also includes things such as reading the title of a DVD they rent, reading posters, and pointing out little architectural details as they wander around (Tom’s character studied architecture).