The name "Qohen Leth" references "Qoheleth" (sometimes transliterated as "Qohelethin" or "Koheleth"), the original Hebrew name (and presumed author) of Ecclesiastes--the Bible book that investigates the meaning of life.
In order to select the locations, Terry Gilliam used Google Earth: "I'd got most of the locations sorted out by using Google Earth before I first went to Romania. This is how we do location scouting these days."
Over half of the film's action takes place within the dilapidated chapel, and this was built as a single, closed set. For Terry Gilliam, the chapel is a metaphor for old beliefs and systems. The chapel's design brings together both English and Romanian churches according to Production designer David Warren: "We came to Bucharest, and had a look at the Orthodox churches here, and they have a very different architecture than Anglican or Catholic ones, in the way the interior is plotted out. We liked the fact that their inside walls are heavily frescoed or painted with all these saints. Terry liked the idea that Qohen is agoraphobic, yet is surrounded by faces all the time. There are faces at screen at work, there are faces following him around in the advertising and even when he gets into his little chapel, there are faces everywhere. So the chapel has an Orthodox interior feel, but the way it is planned out and plotted out, in cluding an organ loft, a high altar, and an entrance vestibule, it is recognisable as Anglican." Warren had 9 weeks to get this complex set built, dressed and ready for shooting.
Cinematographer Nicola Pecorini decided to shoot on film rather than digitally: "Both Terry and I were convinced that the best way to capture the image was on film. It gives you the latitude; it gives you the greatest palette to work with." The 35mm negative was processed and digitized overnight by Kodak Cinelabs Romania located nearby in the center of Bucharest. Digital rushes were available to view in the morning.
The "futuristic" little cars that make crossing the street difficult for Qohen Leth (near the beginning of the movie) are called "Twizy", made by Renault, and were released in 2011. The Renault Twizy is a completely electric car.
The shooting schedule comprised of 36 shooting days, which involved 28 days in the studio, and 8 days on-location using 9 different places. Pre-production in Bucharest officially began on Monday 13 August 2012. Principal photography began on Monday 22 October 2012 and ended on the 4th December 2012. The production shot for 37 days and only went one day over schedule.
The film's production budget used to be $20 million, when it was planned to shoot in London, UK. Later it was decided to move the production to Bucharest, Romania, and the movie finally could be made for only $8.5 million.
Scriptwriter Pat Rushin and his wife Mary can be seen as extras in one scene. They're visible in the background, sitting on a park bench. Mary is reading a newspaper and Pat is writing on a briefcase. He's actually writing lines for the scrolling "Mancom Motivational" messages seen throughout the film.
Director Terry Gilliam praised the creative costume designs by Carlo Poggioli: "Carlo has been amazing. And had it not been for Bucharest, we wouldn't have found the Chinese market, where he has been buying all his fabrics. The costumes are quite extraordinary: man-made fibres that are extraordinary looking, but painfully miserably to wear! We wanted to create this happy world, so with these mate rials we have colours, textures, reflectivity and transparency."
In pre-production, Terry Gilliam suggested that his team should study the work of contemporary German painter Neo Rauch, whose surreal works contain a rich blend of colour. Production Designer David Warren recalled the initial instruction: "I remember getting an email from Terry: Neo Rauch plus Ukelele equals The Zero Theorem (2013). In fact Rauch's work was pinned up on the walls of the art department, and every time Terry used to come in, he asked 'Well, can you get Neo Rauch in?' I said,'I'm trying really hard mate!'" The inspiration from Rauch was indirect according to Gilliam: "His work has so many things crammed in - elements from different centuries, and different colours - that normally you would think were disconnected, and that aspect is here in the film. We mix styles: It's in the near future, but it's also very retro. There are parts that are very garish, and like Neo Rauch, they are shocking, yet quite wonderfully beautiful."
Many were convinced that Robin Williams appears on one of the billboards at the beginning of the movie (at around 4 mins) as the spokesman for the Church of Batman the Redeemer, but Terry Gilliam has since said that it's definitely not him. It might instead be percussionist Ray Cooper who has worked with Gilliam before and has been mentioned as having been involved in The Zero Theorem.
The film was finished in a 16:9 aspect ratio instead of the usual 1.85:1 or 2.35:1 to ensure that it would look exactly the same on the screen of any device, which is why it has round edges on frame corners like a vintage movie.
Qohen has 2 nicknames in the film: Quinn (by Mr. Joby) and Q (by Bob). Rupert Friend, who appears on a billboard in the beginning of the movie, plays a character named (Peter) Quinn in Homeland (2011) and Ben Whishaw, one of the doctors, plays Q in Skyfall (2012).