In the DVD commentary it is mentioned that when shooting the scene in which Donna learns about Josh's serious injury, Richard Schiff, instead of using the line in the script, told Janel Moloney, playing Donna, that "Bradley Whitford died", prompting her absolutely devastated expression in the scene.
Between the previous episode and this one, Moira Kelly's character Mandy disappears from the show and no mention of her character is ever made again.
This episode contains the largest number of guest stars in the entire series.