Throw It In: Much of the more comedic lines were reportedly ad-libbed by the actors. Also other little things, such as Crichton's nickname for Chiana ("Pip") being Ben Browder's nickname for Gigi Edgley.
Chiana was originally not part of the cast, and her first appearance, she was supposed to die. However, the cast and crew liked her so much they let her live and made her a main character.
Melissa Jaffer joined the regular cast at the end of the third season after playing two different guest roles in the second: the aged Nilaam in "Vitas Mortis" and the female Pilot in "The Way We Weren't"
Linda Cropper played the female Plokavoi... Plokavian interrogator in "The Ugly Truth" before being cast in the recurring role of Xhalax in the third season.