Part 1
—I came up with the Blue Moon festival on a whim. Originally it was going to be the Summer Sun festival, but I altered it.
—Twilight bumping into Flash is a nod to Equestria Girls.
—I mentioned in The Pony in the Gray Trilby that Phillip is an ex-Guard. Seems he left behind a reputation.
—Blue Pony Group: a reference to the Blue Man Group.
—That's not what Guards normally say: the dialogue between Phillip and Flash is a reference to dialogue between Sherlock Holmes (Benedict Cumberbatch) and John Watson (Martin Freeman) in the episode A Study in Pink from the TV series Sherlock.

Part 2
—In the Phillipverse, Blueblood is a Duke, not a Prince.
—Mooncakes are a Chinese bakery product traditionally eaten during the Mid-Autumn Festival. They are round pastries with a thick filling and thin crust.
—The fact that Twilight doesn't have a section of Royal Guards attached to her in the show does make sense, as it would probably add quite a lot of complication and confusion. However, it does make sense to me that she should have at least one Guard.
—Agatha Canter: ponyfied version of mystery author Agatha Christie.
—T.S. Equine: ponyfied version of poet T.S. Eliot.

Part 3
—As Twilight and Flash's dialogue reveals, this takes place after the Season 4 finale.
—Course he's not the foal's father!: reference to a scene from the Sherlock episode A Scandal in Belgravia.
—BNP: ponyfied version of the military expression FNG, meaning "F***ing New Guy."
—Sometimes I think everypony hates me: a reference to the all-too-common Flash Sentry hate among the bronies.
—Note that Phillip's crime sense warning is accompanied by a shiver, indicating that his friends are in danger.

Part 4
—Note Blast Cap's behavior. The worst thing that any investigator can do is form a theory before they've gotten all of the facts.
—I believe that there are guns in Equestria (we don't see them because it's a children's show): recall that in May the Best Pet Win, Rainbow Dash said she wanted a pet that was "as fast as a bullet," and she named her tortoise Tank. Also recall that in The Cutie Mark Chronicles, Scootaloo mentioned a cannon.
—The purplish discoloration on the corpse's legs is called livor mortis, or lividity. It's caused by blood being pulled by gravity into the lower parts of the body and can be used to establish a rough time of death.
—I came up with the idea of Flash being good at detective skills from the scene in Equestria Girls when he finds the photographs in the trash.

Part 5
—Originally, Flash was going to be afraid of water and couldn't swim, but then I realized that that was kind of silly, considering that he's a Guard. The claustrophobia came from his being a Pegasus, a species that I imagine relies primarily on mobility for survival.
—I intended for Flash to have more of an "average guy" backstory—good home, good parents, did well in school—really, I did! But then I decided to go with the poor kid with a single parent backstory. It's something I intend to build off of in a later story.
—In real life, cutting a wire on a bomb is actually a bad idea. Usually, bomb squads take the bomb to a safe place and let it explode harmlessly.

Part 6
—I imagine Rarity would have really hated to do a plain suit.
—Flash walking into a wall is another nod to Equestria Girls.
—Luna's speech reflects the spirit of the Blue Moon Festival, which I fashioned as a rough equivalent to Thanksgiving.
—Blueblood had it coming.
—Flash dancing with Twilight is also a nod to Equestria Girls.
—Anpony and Clovenpatra: a reference to lovers Marc Antony and Cleopatra, whose lives both ended in suicide.
—I imagine Phillip being a fan of swing and electric swing like Parov Stelar. Catgroove is one of my favorite dance songs.

Author's Notes:

Chapter notes from the story.