Was there really and explosion?

Yes, I think so... But Mrs. Delahanty had had such an awful reality for most of her life, she shaped a better world in her books. It was her way of approaching most things... I think she always knew what was real and what was not. Aimee was real and her need for loving was real, and she knew about that.

I do think that the explosion was real, because how else could the five survivors come together for their collective healing!? It wouldn´t make sense if this part of the story was only a metaphore or a symbol instead of something that really happened.

But I must say that your interesting statement makes me look entirely different at the movie. :)

i just saw the movie for the second time and i agree with you. the explosion did not happen. when she closed her note book in the train, thats when she finished the novel, taking the people seated around her for inspiration. the explosion is how her novel begins. so the "explosion - end of the movie" was just a fictional story that she made up in the train. this has to be it because the narration when she closed the book and narration right before the end of the movie was identical.

There is nothing that would lead us to believe that it was a novel. If we saw her writing, reading her notes, selling book, anything with written or printed material, that could be a hint. Otherwise there would be no logic to make about 97 percent of a movie just characters imagination and not explain it. There are movies and stories where dreams take mmost of the time (from Femme fatale by de Palma, to clasics like Alice in Wonderland or Wizzard of Oz).

Also, when she looks at people in the train, she really analizes them as if she could write a novel. But in days after the explosion there is a big change, because Werner appears to be someone completely different. If she wrote a book in the train, he would be a person that she imagined him to be.

However, the end when Emily is leaving with words about today that should be lived and tomorow that is not certains leads to another (also unverifiable) idea: Emily might be severely wounded in explosion, and the events are her agony dreams, so when she is leaving the garden (and her new family) she is in fact finally leaving this world. This could be compared to movies like Chabrol's "Alice ou la dernière fugue" and Lynne's "Jacob's Ladder", maybe even "Donnie Darko" (if you neglect its SF theories). All these movies have title characters who are dying from opening scene or few minutes later, to the last minute when we understand it. But in all those movies the plot is a nightmare, while Emily find idyllic peace, so this theory is also weak.

Reading everybody's comments made me realize YES, the whole thing was made up!
As marquischachar remarked:
"The narration when she closed the book and the narration right before the end of the movie was identical." Indeed, she talks about a girl in white at the beginning, making us think about a young woman, but then a the end, we see that the woman is her !

Emily's character tries to establish some sort of contact with her fellow train passengers, when it is clear that they are all busy elsewhere. So she looks for a way to become important to them and fiction is the perfect medium.

Watch the so called explosion again: Aimee walks up toward the window and puts her hand out to us, is if saying : "this is my story".

Everything is made up, Maggie Smith's characther being abused by her father and other men-such dramatic images are an easy ingredient for a "juicy" story.
One IMDB user mentioned that victims of abuse adopt promiscuous attitudes because they know this works to get attention. I totally agree. However, if Emily had really been really abused she would have developped that attitude towards ALL men, not just Aimee's uncle. And she showed such propriety and politeness with the coronel, the German fellow, the inspector and even her butler that it tosses that possibility right out.

No, Emily's class and demeanor is not the one of the helpless young girl/woman she descibed herself to be.
The house itself depicts nobility, education, and old money. A house that's been passed on for a generation or two. Not something she can whip up on her own. Her own new edition romance novels seemed very out of place there. I was expecting Shakespeare or Tennyson.
And Aimee's uncle! He couldn't have been more repulsive and unlikable, coming out more from a novella than from real life.
Wermer's kiss to Aimee at the end was very novelike as well. All that we needed was "I'm sorry".
And to the user who is wailing about the little attention paid to the italian maid, it was just a character she put in the story, however, Emily didn't put much thought into her, so it didn't go anywhere.
Clever movie, don't you think?

The explosion is entirely in the mind of Emily and it provides an inspiration for her next book. Remember, she is always the principal character in these books but with a different name and identity (and bio) for each new book, and there is always a happy ending. So when she starts a book, she must not only choose her characters and work out the plot, she must also create a new identity for herself and a new back story. So after the "explosion" takes place in her imagination, she sits in the train and works out the details of the plot and the interaction of the characters... and this becomes the film.

The new novel will have young Aimee as the other principal (instead of the usual male romantic figure). Aimee's parents must be eliminated for the plot to work, also the General's unpleasant daughter, and Werner's local girlfriend, who would not fit into the house-sharing arrangement The "explosion" neatly takes care of all this. Aimee's straight-laced Uncle Tom is brought in later to supply the conflict every story needs.

But first the Emily character must have a bio, and she starts on this "in the hospital" with her unscathed notebook. And what a lurid tale she concocts: daredevil parents, abandonment, addiction, and white slavery in Morocco! No one would believe this stuff except for the bimbos who buy her romantic bodice-buster tales. Emily also makes her own character into a lush to serve her plot: as a lonely old lady looking for love, she must try to seduce the nasty puritan uncle, and he must resist her advances in order for the required "happy ending" to occur. The real Emily, the successful author of a dozen books, is a cultured and genteel English lady....but also a highly professional storyteller adept at creating nefarious characters when necessary.

There are clues to this scattered throughout the film. The first meeting of Werner and his girlfriend is imagined by Emily, as she freely admits. Likewise the character of Francine, Uncle Tom's wife, is also Emily's creation. And thruout the film, Emily describes her "dreams" which all seem to affect the
storyline she is devising. When she has trouble with the fate of a minor character (i.e., the German boy) he is simply dropped from view without any plausible explanation. Watch the film again and see if this doesn't all make sense to you.