When the Doctor and Adric exit the TARDIS, the normal inside of the Police Public Call Box can be seen.
You can tell that most of the shots of outer space are still pictures.
The Cybermen archive contains information about Cybermen's encounter with the Fourth Doctor. The episode "Revenge Of The Cybermen" takes place in their future. It's placement suggests that "Revenge Of The Cybermen" took place before "Earthshock", which is the year 2526. According to the Doctor in "The Ark In Space", when he first steps out onto the station, the Nerva Beacon is 29th or 30th century technology. Viewers have speculated that the "Revenge Of The Cybermen" clip is possible because the Cybermen had travelled back in time to prevent the Cyber Wars - which would also explain their more advanced design. There is nothing in the episode itself, however, to support this notion.