Arzu Bazman's character should originally be named Isabell. However, Bazman did not like that name, so she successfully suggested to give the character her own first name, Arzu.
Bernhard Bettermann, Rolf Becker, Michael Trischan and Anja Nejarri all played episode roles in the series before becoming regular cast members.
Michael Trischan has stated he has watched the series from the first episode on and always wanted to be part of it, before finally getting the role of Hans-Peter Brenner in 2007.
Fred Delmare had to leave the series after being diagnosed with Alzheimer's disease in 2005; his last day of filming being on 7 November 2005.
After her character, Pia Heilmann, had fought breast cancer in the series twice, actress Hendrikje Fitz was really diagnosed with the disease in 2014. After a first successful treatment, metastases were found in her brain in the autumn of 2015. For that reason, she had to reduce her filming work for the 19th season, which was aired from January 2016 on (her character took a sabbatical in Italy). In October 2015 she filmed several scenes at her own family's house near Monterotondo Marittimo, Tuscany. In January 2016 she filmed one last episode at the MDR studios in Leipzig. Three months later, Fitz died from her disease on 7 April 2016, aged 54. Her last episode was aired posthumously on 27 April 2016. Six months later, on 11 October 2016, she made one last appearance in the series, with one of the scenes filmed in Tuscany in 2015, which she personally selected to be her last scene: She was seen walking away through a sunny Tuscan alley and spreading her arms. In the episode, Pia sends that scene to her family in Germany as a video message, adding she would "go on a longer trip next week". One week later, in the episode of 18 October 2016, the character's death was announced.
Michael Trischan really worked as an examined nurse before starting his acting career.
Bernhard Bettermann claims that one time, a few years after he had joined the series, he was on an airplane and accidentally raised his hand when the crew asked if there was a doctor on board. Luckily, there were other "colleagues" on the plane who could step forward.