Back translation is a common technique to assess the accuracy of translation, but its application in different contexts is often subject to controversy. The aim of the present paper is first to check the appropriateness of back translation for movie subtitling purposes on the one hand and on the other, to see which technique leads to a better translation, collaborative translation or back translation. To achieve this aim, 50 Persian sentences with problems in their translations were randomly selected from Harry Potter and the Philosopher’s Stone subtitled by Kalhor (2001), the most commonly used subtittled version of this movie in Iran, and tested through back translation technique. The participants of the study were 90 undergraduate students of English translation at the University of Isfahan who had already watched the movie. The new translations suggested by the participants were then compared with the translations made in a collaborative way. A comparison of different versions of the sentences proved that back translation is an appropriate technique for testing the translation of subtitles. It was also revealed that students involved in collaborative translation outperformed those using the back translation technique.