UK: "The final episode depicts Sam waking from his coma, only to find the modern world devoid of feeling compared to his life in 1973. He ultimately takes a joyful leap from the top of the police station, returning to the past. Writer Matthew Graham wrote the scene to indicate that Sam is now in the afterlife, but acknowledged that the ending is ambiguous and open to other interpretations, such as lead actor John Simm's belief that Sam may not have returned to the present.[11] In the first episode of sequel series Ashes to Ashes we see DI Alex Drake with Sam's 2006 era personnel file which has the word "SUICIDE" stamped upon it."
US: "At the end of the series, it is revealed that Tyler's 2008 and 1973 realities were both fictitious, created by the onboard computer of a spacecraft that is carrying Tyler, Hunt, Norris, Carling, and Skelton on the first ever manned mission to the planet Mars, in 2035. The crew he worked with in 1973 were just virtual reality versions of his fellow spaceship crewmembers. His room number, "2B", is his sleeping unit; his old precinct, "Hyde 125", is his identification number; his neighbor, Windy, is the name of the computer A.I.; Frank Morgan, an FBI agent in the series, is the Mission Control flight director. To sustain the crew, their minds were routinely kept active while asleep using virtual reality "neural stimulation" programs of their own choosing, but Sam's choice of a scenario where he was a police officer circa 2008 was abruptly changed to a 1973 setting by a meteor-storm induced glitch in the computer. This conclusion is markedly different from the conclusion of the original UK series, but is still left ambiguous as the first step on Mars depicts Gene Hunt's signature shoe stepping into the sand."