The article analyses the textual changes that occur in the process of staging a performance based on a translated text. Drawing on Morini’s four types of theatre translation, namely the interlingual, intralingual, intersemiotic, and intrasemiotic aspects of theatre translation (emerging from Jakobson’s classification of translation), the article focuses on the differences between the translated text and the text spoken on the stage through the analysis of the Slovene performance of Sad Songs from the Heart of Europe by the Finnish author Kristian Smeds, translated into Slovene by Julija Potrč Šavli. The play, directed by the Finnish theatre director Jari Juutinen, was performed at the Slovene theatre Slovensko ljudsko gledališče Celje by the Slovene actress Maša Grošelj. As the author of the article participated in staging this play as a language consultant, the article provides an insight into the process, and reveals why and how the changes to the text occurred. As the analyses of the written and staged texts show, the majority of the textual changes were introduced by various agents involved in the production of the play, while some were also due to the multimodal interactions between different theatre modes (speech, scenography, sound, light, props, etc.).