Rose Tyler makes a brief cameo at the very end of the episode.
When Donna Noble was ready to leave in the TARDIS, she left the car keys in a litter bin for her mother Sylvia to collect & she told Sylvia this by phone. Donna then spoke to a blonde bystander to ask her to tell Sylvia which litter bin the keys were in. After Donna had left, the blonde turned to face the camera & we saw that it was Rose. Rose then walked away & faded out. (When she turned to face the camera, Rose's theme from "Doomsday" began playing & it continued until she'd vanished.)