So how were the staff able to clean the room, and the police document all the suicides? Surely all that must take more than one hour.
Olin does explain that he strictly supervises the cleanings with the door open and makes sure that nobody's in there for too long. Presumably he followed a similar procedure for the police. Police investigators would also be highly unlikely to be in the room alone
Perhaps the room is "intelligent" in a way, and only kills people who actually make reservations for the room with the intent of staying the night.
Or it only kills people when it can reasonably expect not to be widely recognized as a dangerous Genius Loci by so doing. It isn't endangered by Olin knowing about it because Olin can't tell anyone about it and be believed, and it isn't endangered by the occasional "natural death" that befalls someone who's recently entered it, but if almost everyone who walked past the door dropped dead on the rug five seconds afterward, sooner or later the world would notice and intervene.
Mike hears that nobody has been able to remain in the room even an hour, with times to suicide ranging from a few seconds to a few minutes. However, after we learn how the room works, one realizes that those brief times were only in the beginning of the latest loop. We don't know how many loops they'd endured up till then.
It is doubtful that this is really a time-loop rather than a case of time hyper-extended (see Headscratchers for supporting evidence). Not that it made any difference for the victims (Mike obviously "experienced" a much-longer-than-an-hour period during his ordeal) but, if so, it could mean that at least theoretically there was a possibility of enduring several such cycles and then getting out of the room successfully - in the morning.
With that in mind, now think about the "natural deaths" that also occurred in that room...
Given the room's evil and macabre sense of humor, how likely is it that the "express checkout" is Schmuck Bait, and suicide would lead to being trapped like the ghosts we see in the room?
There was a dead guest who had been found trying to stitch his neck closed. Presumably after he had taken the express checkout option something convinced him this was an error in judgement.
What if the ending is simply Mike trapped in yet another loop?
In the short story, Mike realizes that whatever is wrong with 1408, it was never human. So what the hell was it?
If 1408 is truly, as Olin said, "an evil fucking room", who's to say what if the entire 14th floor is the same way? While not as powerful as 1408, there are eerie signs of the entire floor acting that way. Such as when Enslin walks through the floor as he observes the evidence Olin gave him of 1408, with very unsettling noises coming from the other rooms, one housekeeper, and even a plate of food left on the ground with flies around it.
In the short story, Mike's random utterances, while making sense from the reader's perspective, would (and, indeed, did) terrify an in-universe listener - imagine pressing play on that tape recorder and hearing "Orpheus on the Orpheum Circuit!", "fuming oranges", and "that's not a real plum; that's a plastic plum" with absolutely no context.
Before stepping onto the ledge, Mike says into the recorder that the room didn't win... but if he really fell down, chances are that the recorder would just smash into pieces, thus burying the evidence of Mike's "victory" forever.
The room blocked the cellphone, but didn't block the laptop. Why? Because there's been people in there to clean, and it's pretty likely that at least one of them has had a cellphone in their pocket. The room would figure out what those things are pretty fast - it's already figured out the phone lines, after all. However...it's never seen a laptop before. If the last paying visitor was in 1978, it's never even seen a computer before. So the laptop surprised it, which is why Mike got through on the wireless. It then broke it to stop him from doing that, and then once it had figured the computer out, decided to use it against him to get more victims. Because even evil hotel rooms need toys.
Although magnetic keys don't work due to a scrambling of anything electrical, it does sort of raise the question of why the laptop works at all.
Or how there's wi-fi.
Maybe there was neither - the room may have been dicking him around...
