Filming
Eastwood and Burton reportedly dubbed the film 'Where Doubles Dare' due to the amount of screen time in which stand-ins doubled for the cast during action sequences. Filming began on 2 January 1968 in Austria and concluded in July 1968. Eastwood received a salary of $800,000 while Burton received $1,200,000. This is one of the first sound films to have used front projection effect. This technology enabled filming of the scenes where the actors are on top of the cable car.
Eastwood initially thought the script written by MacLean was "terrible" and was "all exposition and complications." According to Derren Nesbitt, Eastwood requested that he be given less dialogue. Most of Schaffer's lines were given to Burton, whilst Eastwood handled most of the action scenes. Director Hutton played to his actors' strengths, allowing for Burton's theatrical background to help the character of Smith and Eastwood's quiet demeanour to establish Schaffer. Eastwood took the part on the advice of his agent, who felt it would be interesting to see his client appear with someone with seniority. Eastwood and Burton got along well on set. Ingrid Pitt had spent part of her childhood in a concentration camp and reportedly found it uncomfortable to work on the movie.
Derren Nesbitt was keen to be as authentic as possible with the character of the suspicious Major von Hapen. Whilst on location, he requested to meet a former member of the Gestapo to better understand how to play the character and to get the military regalia correct. While dressed in his SS uniform, he caused a Baron to faint with shock and found out that he was Himmler's driver. Nesbitt said that the "Jewish Chronicle called me afterwards and said, 'How could you play a German?' I said 'I do it because I play them very badly.' That seemed to satisfy them." He was injured on set whilst filming the scene in which von Hapen is killed. The blood squib attached to Nesbitt exploded with such force that he was temporarily blinded, though he made a quick recovery.
The filming was delayed due to the adverse weather in Austria. Shooting took place in winter and early spring of 1968, and the crew had to contend with blizzards, sub-zero temperatures and potential avalanches. Further delays were incurred when Richard Burton, well known for his drinking binges, disappeared for several days, with his friends Peter O'Toole, Oliver Reed, Trevor Howard and Richard Harris. As part of his deal with Metro-Goldwyn-Mayer, Clint Eastwood took delivery of a Norton P11 motorcycle, which he 'tested' at Brands Hatch racetrack, accompanied by Ingrid Pitt, something that he had been forbidden from doing by Kastner for insurance purposes in case of injury or worse.
Stuntman Alf Joint, who had played Capungo – the man whom 007 electrocuted in the bathtub in Goldfinger – doubled and was stand-in for Richard Burton, and performed the famous cable car jump sequence, during which he lost three teeth. Joint stated that at one point during production, Burton was so drunk that he knocked himself out while filming and Joint had to quickly fill in for him. Derren Nesbitt observed that Burton was drinking as many as four bottles of vodka per day.
Visitors to the set included Burton's wife Elizabeth Taylor,
and Robert Shaw, who was then married to Mary Ure.
At one point during filming, Burton was threatened at gunpoint by an overzealous fan.
The Junkers Ju 52 used to fly Smith and Schaffer's team into Austria and then make their escape at the end of the film was a Swiss Air Force Ju 52/3m, registration A-702. It was destroyed in an accident on 4 August 2018 in Switzerland, killing all 20 people on board.
The castle setting was Hohenwerfen Castle, Werfen, Austria; filmed in January 1968.
Filming of the cable car and lower cable car station took place in January 1968 at the Feuerkogel Seilbahn at Ebensee, Austria, and the close-ups were done on a soundstage. Scenes featuring the castle and the cable car together were filmed using a scale model.
Airport scenes were filmed at the Flugplatz at Aigen im Ennstal, Austria; filmed in early 1968. The exact place of filming is the "Fiala-Fernbrugg" garrison, still used by HS Geschwader 2 and FlAR2/3rd Bat. of the Austrian Army. The big rocky mountain in the background of the airfield is the Grimming mountains, about 40 kilometres (25 mi) east of the "Hoher Dachstein", or about 80 kilometres (50 mi) east and 10 kilometres (6.2 mi) south from Werfen.
The village setting was Lofer, Austria; filmed in January 1968.
Other scenes were shot at MGM-British Studios, Borehamwood, England; filmed in spring 1968.
