Other issues included the studio's desire to substitute Montreal or Prague for Paris in order to lower costs, Liman's insistence on the use of a French-speaking film crew, and poor test audience reactions to the film's Paris finale. The latter required a late return to location in order to shoot a new, more action-oriented conclusion to the Paris story arc. In addition to Paris, filming took place in Prague, Imperia, Rome, Mykonos, and Zürich; several scenes set in Zürich were also filmed in Prague. Damon described the production as a struggle, citing the early conflicts that he and Liman had with the studio, but denied that it was an overtly difficult process, stating, "When I hear people saying that the production was a nightmare it's like, a 'nightmare'? Shooting's always hard, but we finished."