Except for three shots, the entire film was shot on a single Soviet anamorphic lens. It was as cobbled together as it gets. The glass elements themselves, if closely inspected, were a myriad of scuffs and scratches. But these imperfections led to the very unique look of Mouse. The lens itself had to be repaired and completely disassembled on-set no less than 2 times by cinematographer Derek Mindler.
The film actually takes place in both Summer AND Winter. In order to achieve this the production had to go on a five moth hiatus. The first two Acts were filmed in mid-September and returned to finish the production with a five day shoot in February.
A small detail can be seen all though out the film is that all of the traffic lights and crosswalks are shining RED. Significant time had to be spent waiting for the lights to go through their set pattern to time these shots; as the production did not have control over the street lights.
"The Wounded Bird" a painting that was the MacGuffin and main object of desire in one of Engels earlier films "On a Country Road" can be seen on the wall in Michael's basement apartment. Historically, any owner of that fictional painting is doomed.