In the final mission to capture Admiral Harkov, two previously destroyed Corellian Corvettes re-appear again as active starships.
Early in the first campaign, the Nebulon-B Frigate "Fogger" reappears as a Modified Frigate (a completely different class of starship) in the short space of one mission.
In missions where there are no primary objectives, the Secret Order envoy speaks in the voice of the briefing officer who normally gives the end-of-mission briefing summary.