Season 4 cast changes: Conrad Coleby (Dutchy) replaced Jeremy Lindsay Taylor (Buffer). Danielle Horvat (Bird) replaced Saskia Burmeister (Nav). Jay Ryan (Spider) was not replaced. Although not a crew member, Tammy Macintosh (Knocker) replaced Steve Bisley (CMDR Steve Marshall) as the shore commander. None of the departures were explained other than CO's comment near the end of Red Reef (2009) that some members may be transferring at the end of their tour. All four of the actors that were replaced had been in the series from the beginning. All of the replacement actors would remain through the end of the series.
In the Blu-ray boxset from Germany this episode's title is "Licht and Schatten".