Although the show had plans for a second season, the first season's storyline did play out as intended.
In this interview, series creator Kyle Killen talks about some of the theories he's seen and his thoughts on them.
Just to confirm: The season finale played out exactly as you always intended it, even knowing that renewal was looking iffy?
It really did. I mean, our ratings weren’t great, so there was some suspicion that we might not be back, but nobody had any idea what NBC would do. And literally, that last scene was something we had talked about from before the pilot was even written.
So season one did conclude as intended.
Obviously there has been much speculation about what the heck we watched last night. Will you go so far as to say that it was not all a dream? That there was a car accident?
I’ve seen some really interesting [theories], and I wouldn’t say that anyone is wrong — except the people who are calling it a Dallas or a Newhart, any variation on “…and then he woke up.” That is absolutely not what we intended.
But there were many things that weren't included in season one, and would have been put into season two:
That was my next question, what Season 2 would have looked like. A similar weekly procedural, but now with an added avenue through which Britten could glean clues?
For us, the balance of his personal stories versus the procedural would have taken some time to work out. Toward the end of the season we become more interested in his personal coming-apart, and the dream space. And though it ended with a positive grace note, it would have potentially been a bigger problem, a sign of things worsening for him. One of the elements we were very interested in involved Michaela McManus, who did a fantastic job as Tara, Rex’s tennis coach and a potential love interest in the [“green”] world. In Season 1, the procedural — really the dual procedurals — crowded out those things….
There's also a second interview with opinions again from Killen.