Hamish was originally called 'Geilgud'.
Trevor was called 'Bollocks'.
JP (short for 'JeanLuc Picard') was originally called 'Bowie', hence why his eyes are two different colours.
Davina was originally called 'Winslett', hence why she wears a similar blue necklace as that worn by Kate Winslett in the film Titanic. Her name was changed because "she looked more like a Davina".
Davina does not appear in the original unbroadcast pilot, she was later added by the writers.
Trevor originally had white fur, but this caused problems when filming the pilot in terms of lighting, becuase he flarred under the studio lights. He was changed to grey before the full series was filmed to combat this problem.