* How exactly did the source code project harvest the eight minutes of memory from every single person on the train?
** Also, if they only have eight minutes of memory, how can they extrapolate the complex identity of a complete person from just that information alone? How could they tap into [[spoiler:an entirely different reality]] where people's reactions and responses have totally changed in unpredictable ways from just eight minutes?
*** Because they're not extrapolating from memories, they were "setting up a quantum reality" based on hazy handwaving stuff about "how the brain works."
* Just how is Colter supposed to permanently take on Sean's identity? He doesn't know anything about the guy that isn't on his driver's license... Moreover, ''why''? What's the reason for keeping everything a secret from everyone besides Goodwin?
** nobody would believe him. so he just needs to look up stuff when he gets to his home, find out his SSN and whatnot from his own documents. then he quits his job as a teacher and lives on.
*** Rutledge's talk about how Colter is so similar to Sean in physical manner and synaptic maps may also have something to do with it. [[EvictedElement This Troper]] doesn't exactly know what a "synaptic map" is (something to do with the mind obviously), but the similarities could mean they also have resemblance in personalities. While not completely alike, Colter could jump into Sean's shoes and people would see little difference beyond Colter's lack of experience with those people.
**** Except we know that there is at least some difference in personalities. Christina mentions it. And a similar personality doesn't really matter. If Colter (as Sean) bumps into someone on the street and doesn't recognise him, it could get really weird. For example, if it was Sean's father or cousin, or his best friend.
** Fake some sort of trauma, tell people you changed and had amnesia.
* Colter is constantly told that he only has eight minutes, as that is when the bomb on the train goes off. However, he gets off the train twice, and both times is also killed. At the very end when his last eight minutes are up, [[spoiler: nothing happens. He's free to go about his new alternate life]]. So all Colter had to do to get out of it was [[spoiler:not get killed any of the previous times he was sent into the Source Code]]. The eight minutes meant [[spoiler:absolutely nothing at all, other than that was how far he could go back, and not how long he had inside the Source Code]]. He could have just [[spoiler:walked off the train and the Source Code project would have been complete and total failure]].
** Until he got unplugged for failure to complete his mission on that pass. He was only [[spoiler:free to go about his new alternate life]] because [[spoiler:the plug had been pulled on his original body, creating a new quantum reality for him to live in]]. The movie as a whole seems to be precipitated on exploring the ideas of [[http://en.wikipedia.org/wiki/Quantum_suicide_and_immortality quantum immortality]].
** It's actually clear before that that the eight minutes meant nothing, because there was also the time when he delayed the bombing, putting him over his limits, and the time when he wasn't on the train and saw the bomb go off in the distance. I'm very curious about whether or not the other people in the lab knew this or not ... I mean, simple testing would have shown that it's not a simulation or "shadow". It did occur to me that perhaps we're seeing the very first run of the system, when they have barely worked out what the technology is capable of.
*** Which, in and of itself, also makes no sense. How is it possible that the guy who invented Source Code didn't know that it could [[spoiler: create entire alternate realities and send the subject into them]]?
*** It's possible he didn't know the complete capabilities because he just wasn't looking for that; after it was clear the basics were covered, maybe nobody bothered to dig any deeper into it.
** Colter only has eight minutes because after the train blows up it's practically impossible to investigate any further. Why eight, exactly? Because that's [[TechnoBabble how far back they can send someone]] into the life of a doomed person (or whatever Sean actually is). But the train blowing up is the important part; there's no point staying in the Source Code after the bomb has gone off and the terrorist has got away. We saw two timelines in which he got off the train and/or delayed the blast but died anyway, but those look like either {{Railroading}} (pardon the pun) by [[AnthropicPrinciple the authors]] (can't have a plot if he loses track of the investigation), or YourMindMakesItReal (he died because he believed he had to die!).
* Why did Colter encourage Goodwin to stick with the program, and not just let him die in his message to the alternate reality? It seems that the original Colter preferred to die rather than continue with Source Code, so why is he pushing the undesirable fate onto his other self?
** Colter was all right with the idea of stopping terrorists. He said in the text for Alternate!Goodwin to "help him" and "tell him that everything's going to be all right". I assumed that he meant that Alternate!Goodwin should make sure that Alternate!Colter is told the truth about what he is and, if Alternate!Colter asks to die, he should be allowed to die. Basically, he wants her to treat him well.
* Are there two copies of Colter's consciousness in existence at the same time [[spoiler:in the alternate reality at the end of the movie (or in any of his Source Code excursions for that matter)? One in Sean's body and one in Colter's at the project's headquarters. Could he go talk to himself?]] What happens if the process gets repeated? Can he end up in [[spoiler:a parallel universe with almost all humans being controlled by Colter]]?
** Nope. Because they said, he has to be a match, Sean was only picked because he was a close match to Colters sex, size and brain map/whatever. He couldn't inhabit women's bodies, children's, shorter men, people with brains too different. Though ofc this scientist didn't realise it could make an alternate reality, so maybe he could inhabit more bodies than he first expected too?
** Yes, there are two Colters in that last timeline.
*** But it's worth noting that if and when the Colter in the Source Code Project gets used and ends up creating another reality his consciousness will move on to that reality while the Colter we spent time with will stay where he is. Assuming nothing in the Project's approach changes there'll only ever be a maximum of two Colters in any reality, one free, one in the Project.
**** But all of those universes will spawn from the one where Colter took over Sean and saved everyone on the train. So, if there are only ever two Colters (the free one and the Project one), does that mean the real Sean suddenly does everything Colter did?
* Whenever Colter travels to that alternate universe thingy and inhabits Sean's body, he's pretty much reliving the last eight minutes of his life, so I guess it doesn't really matter that he traveled to a parallel universe and took some guy's body because he's going to die anyway. But Sean doesn't die in the last one! Colter took over his body!
** Except there never was a Sean in that universe. People have memories of Sean and such, but the universe was created the moment Sean/Colter woke up. In essense, Sean's body is an empty shell.
*** That's assuming it's reasonable to extrapolate from the false information supplied by the creator/director of the program, as well as Goodwin. It's far more reasonable (in my opinion) to assume that it latches onto an appropriate reality that's already one of the infinite infinities of available realities that match the Sean from Colter's Source Code data, unless the epilogue is a [[IronicHell personal-tailored]] [[InvertedTrope heaven]].
** It's not really clear what's "real", but even if Sean was a totally real person just as important as Colter and Colter taking his place is just as bad as GrandTheftMe, Sean only had eight minutes to live. Without Colter there to stop the bomb, Sean was as good as dead anyway. So it's hard to feel too much FridgeHorror about what happened to him.
* Why did they never check her ticket? They always checked his but never hers.
** Easy enough: She gets on one station ahead of Sean. She's already had her ticket checked.
* Rutlege and Goodwin were convinced that the bomber was acting alone and not part of a cell, or at the very least they were the same person who intended to carry out the next attack. Colter never questioned this, so why didn't he make a note of everyone who got off at the stop and limit his investigation to them? Instead, he identifies potential suspects up to moments before the explosion. Even if the bomber had been one of those people and weren't working alone, the various intelligence agencies would only have a few hours to find a dead bomber's cohorts. Rutlege and Goodwin's only play would be to send Colter back into the Source Code and see if he can beat the information out of the bomber.

* Is it just me, or is it implied that the "Goodwin helps Colter" is an infinite cycle? Colter is helped by Goodwin (who, you'll notice, isn't exactly perfectly calm in the beginning), gets into alternate timeline, sends message to Goodwin/2. Goodwin/2 helps Colter/2; he gets into an alternate timeline and messages Goodwin/3... et cetera. The only difference in the "first" run is that we don't get to see its beginning, and so assume it is... but it might have happened countless times before. The whole "everything will be OK" thing adds to this idea.
** It's shown that in the alternate timeline the train never blew up so that is the first time we see the train, although whether he's averting a different disaster each time then living on in a different alternate universe in the body of his host is an interesting one