Cast the Expert: In hindsight, the creators said the only reason this musical became what it did was casting Darren Criss as the star and making use of his skills as a songwriting prodigy. It gets referenced onstage a lot with Harry's guitar (Criss' real-life guitar) essentially replacing the Firebolt as his all-purpose secret weapon.
You can see Tyler Brunsman do this during "To Dance Again", a deliberate result of the show staging Cedric's death so his body would remain prominently visible through an entire showstopping dance number, complete with kick line.
Harry loses it—repeatedly—in the scene at Hagrid's shack. Also, the corpse of Moaning Myrtle in the flashback, but this one is intentional and Played for Laughs.
Cho's verse in "Going Back to Hogwarts" has become this for Darren Criss. In later performances, he either omits the verse entirely (skipping right to Cedric's line) or spends time explaining the context of the line and essentially apologising.
Devin Lytle also regrets accepting the role of Cho, feeling she stole it from Sango Tajima for the sake of a single cheap gag.
Dawson Casting: Played for laughs. All the actors are university. Harry says he's 12/11/17, depending on the play.
Deleted Scene: The original stage production began with Bonnie Gruesen narrating a prologue where we silently see Voldemort murdering Harry Potter's parents. This was cut for time in the YouTube version under the justified assumption all the viewers would already know the backstory.
A similar staging ended up becoming the opening of Starkid's later show, Holy Musical B@man!
Joe Walker actually had a cold during the performance, creating Voldemort's iconic wheezy voice which he then had to fake during all future appearances.
Ron wears a headband because Joey Richter found that it helped the wig stay on better. It's since become an iconic part of Joey's image.
Sleeper Hit: Even before the viral YouTube success, this show that was intended as a lark among college friends was a surprising word of mouth success. Team Starkid describes how right after their opening on Thursday night, they started playing to a packed house every show, with people driving to the University of Michigan from as far away as Chicago for tickets. They ended up having to extend the show to Sunday to accommodate everyone, at great inconvenience to several cast members (see Troubled Production). And then, after they chalked all this up as a wild once-in-a-lifetime he experience, they decided to put the recording on YouTube...
Throw It In!: The creators have revealed assorted tidbits which, added up, ultimately mean that most of what makes the show great was the result of the actors just not caring all that much.
Ron's habit of constant snacking was born of Joey Richter's own habit of doing so during rehearsal. In the performance recorded for YouTube, Ron's onscreen eating is Joey's actual dinner — he didn't get to eat all day before the show so he bought Chinese food on the way and made wolfing it down while trying to get Ron's lines out part of his character.
The notepad Dumbledore uses to run through all the information he has to give Harry was devised by Dylan Saunders because he couldn't actually remember it.
Rumbleroar asking Dumbledore if he remembered his spacesuit was ad-libbed by Jim Povolo, as Saunders had genuinely forgotten it.
Several memorable lines were improvised, like Darren Criss inventing the word "supermegafoxyawesomehot".
Throw It In!: The famous line from Lavender Brown "Bitch, I ain't Cho Chang!" was embellished by Sango Tajima — in the script Lavender simply politely says "I'm not Cho Chang" — and, according to pretty much everyone who's seen it, makes the whole scene (and rescues it from a lot of racist undertones by having the actual Asian onstage defy stereotypes so strongly).
Took the Bad Film Seriously: Nick Lang describes not originally expecting the show to be more than Stylistic Suck when it came to the music — the initial idea was simply that it was inherently funny to turn the Harry Potter books into a musical. However, even under the absurd constraints he was working under, Darren Criss couldn't help but write genuinely good music for the show, and everyone else stepped up the level of their performance in response. The surprising degree to which the songs in the show actually work played a huge role in the show's Sleeper Hit status.
One specific example is how there was clearly very limited time for choreography, but Joe Walker's performance and A.J. Holmes' music really fool people into thinking "To Dance Again" is a fully choreographed number. (Even though, as Joe points out, he's really just walking back and forth across the stage.)
Troubled Production: As noted under Serendipity Writes the Plot, no one took this show terribly seriously at first, seeing it mostly as a lark to entertain their friends. The total rehearsal process lasted three weeks, during which the show was still being written. The songs were either songs Darren Criss had already written ("Sami/Harry", "Not Alone") and repurposed, or were written in a matter of hours and then presented to the cast on the day they were written. The song "Voldemort Is Going Down" was added the day before opening, by A.J during the dress rehearsal, as a last minute change because the Langs decided having the battle against Voldemort be a total Anti-Climax wasn't funny enough. The thought that this show would become a worldwide beloved hit or that these songs would be performed over and over again on tour was the furthest thing from anyone's minds. (Indeed, the lyrics of many of the songs weren't fixed until the cast album made after the show went up on YouTube.)
Not only were there three weeks between casting and opening night, but thanks to poor planning on the Langs' part, almost all of the cast was committed to another play during the first week of rehearsals. Most of the cast only got two weeks of rehearsal, with the exception of Joe Walker and Brian Rosenthal — which helps explain why Voldemort and Quirrell are the two most developed characters. (Joe describes how in the first rehearsal he threw a fork at the ceiling and broke one of the lights, meaning that whole session was wasted cleaning up broken glass.)
The show was such a Sleeper Hit that the Langs and Brian Holden decided to add an extra day of performances to accommodate everyone who wanted to see it — which apparently did not go over well with some of the cast. (Tyler Brunsman felt it was a serious imposition when he had an upcoming exam to prepare for; Jaime Lyn Beatty's parents were visiting from out of town to see the show and the extra performances meant she didn't have any time to visit with them.)
Apparently the Langs actually expected Tyler not to show up for the last show and were surprised when he did — and had no recourse in mind for if he didn't other than awkwardly skipping past his lines and telling the audience to imagine he was there.
Typecasting: This wasn't actually Lauren Lopez's first time in a Cross-Cast Role: Nick Lang revealed they'd cast her as a "tiny little British boy" several times before, including as Frodo Baggins in their parody of The Lord of the Rings.
The show was originally intended as more serious and more faithful to the books
Before Dylan joined the cast, Joe Walker was intended to play both Voldemort and Dumbledore
Brian Rosenthal was at one point considered for the role of Harry and Lauren was considered for Hermione.
Crabbe was almost a basic hand puppet controlled by Goyle.
At the peak of AVPM's viral buzz, Nick Lang was contacted by John Tartaglia (the star of Avenue Q) who wanted to take the show to Broadway on the condition he got to play Draco Malfoy. Unfortunately, having to get the Harry Potter license from Warner Brothers made this impossible.
In a livestream, Darren Criss revealed that he had a different idea for a meta musical that was more of a serious drama telling a realistic life story through the lens of the protagonist being a Harry Potter superfan in his youth. "Goin' Back to Hogwarts" and "When I Was Harry Potter" were conceived as explicitly metaphorical songs about someone who'd hit hard times as an adult yearning to go back to their carefree Glory Days.
A Very Potter Sequel:
Creator Backlash: In response to the backlash over J. K. Rowling coming out as "gender critical" on Twitter, Nick Lang openly denounced and apologized for the character of Umbridge in AVPS being a Creepy CrossdresserCross-Cast Role whose portrayal hurt a lot of trans Starkid fans.
Luna Lovegood's cameo and explanation to why we don't see her in the original.
It's explained why Dumbledore was able to Dissapperate inside Hogwarts in the first Musical when Umbridge questions it after his escape — he never did, he just seems to say "Dissapperate" whenever he leaves a room.
Production Posse: Several of the new characters are played by Me and My Dick alums. Flopsy is Lupin, The Old Snatch is Sirius, Big T is Yaxley, Weenie is Lily, Hedwig, and Luna.
Writer Revolt: It seems the writers/creators have mixed thoughts about their decision to censor and edit A Very Potter Musical to something worthy of a PG-13 once it caught on with younger audiences online. Though censored F-bombs and edits appear in the sequel too, Lupin and other new characters seem to been written specifically with Cluster S Bombs and similar frequent (but PG-13-appropriate!) profanity sewn into their personalities, and in a sly nod to the original censorship, the kid characters (now only eleven!) cover their ears any time Lupin swears.
When the kids go back in time and they see themselves in the past, they're all played by people in the play who look nothing like them. Draco is played by the tallest guy in the show (Jim Povolo a.k.a Goyle) Hermione is played by a husky man (Richard Campbell a.k.a Neville), Ron is played by a much skinnier guy (Brian Rosenthal a.k.a. Seamus), and Harry is a petite Asian girl (Sango Tajima a.k.a. Lavender Brown) in an afro wig.
A Very Potter Senior Year:
Contest Winner Cameo: Starkid ran a promotion where they asked fans to submit a song they wrote or a piece of artwork they designed to be considered for inclusion as part of AVPSY. They were surprised when ''both'" contests were won by the same person, Australian Starkid fan Robert Manion. Unfortunately, they ended up not being able to use either one in the show due to time constraints, but did invite Robert to the performance and later invited him to audition for Twisted once he relocated to the US. As of The Guy Who Didn't Like Musicals, he's a core member of the troupe.
Deleted Scene: A few lines in the script didn't make it to the Youtube release.
A short exchange where Scarfy flirts with a shawl was cut out as well.
They also cut out all of the lines where the Riddles accused Tom of being gay. It could be because the lines actually weren't played for laughs and actually made the scene more depressing.
A second epilogue where Lockhart achieves his dream of being found by mice was not present, probably due to the fact that it takes away from the "Hermione and Lockhart writing the Harry Potter series" subplot.
Right after Hermione accepts Ron's proposal, Dumbledore and Rumbleroar made a cameo. There's no explanation as to why it was removed (if it was even in the live show).
Development Gag: When Harry repeats his "Butterbeer's on me!" line from the original show only for McGonagall to silence the resulting cheers; this is a reference to the original plan for A Very Potter Sequel, which would have picked up exactly where Musical left off, with McGonagall similarly putting a stop to the celebration of Voldemort's defeat.
Enforced Method Acting: The improvised diary rules mentioned in Throw It In! below resulted in a hilariously genuine "Oh shit!" from Joe Walker after Darren decided to bring up how his own earlier ad lib would affect the climax.
Meredith Stepien replaces Bonnie Gruesen as Hermione. In true StarKid style, it is immediately lampshaded. Hermione breaks her nose at the beginning of the musical and fixes it with a spell, but looks different.
Hemione: Well, I may look different, but you guys should just treat me like I'm the same old Hermione you know and love. [To audience] And that goes for all you too. [She winks at audience]
Ironically, the actor named Darren is never recast (if anything, the unwillingness to recast him made it more difficult to get AVPSY off the ground).
Julia Albain was unable to appear, and is replaced by Brant Cox as Percy and Pat Brady as the Candy Lady, while Crabbe is killed offscreen. In an Actor Allusion, the Candy Lady has taken Crabbe's place in Draco's gang.
Production Posse: With only three exceptions, every single actor who's ever been in a Starkid production is in this show. Notable examples includes Elona Finlay from Little White Lie as Madam Pomfrey and Alle-Faye Monka from Me and My Dick as Fleur, both of whom hadn't been used by the company in years.
Growing up, moving on, and letting go of Harry Potter and Hogwarts.
Some of the lines in the show—particularly, a few lyrics in "This is the End" and "Wizard of the Year"—seem like they're not about Harry getting old so much as they are about Darren Criss growing apart from Team Starkid as he finds mainstream fame.
It's also this when you realize this was also supposed to be the final Starkid show altogether, if it's 'growing up and moving on' theme, it's nature as the Grand Finale to the AVPM series as a whole and a massive Production Posse with nearly every single Starkid actor appearing up to this point is anything to go by, with the creator's very next show, Twisted: The Untold Story of a Royal Vizier, meant to be separate from the Starkid name (until a typo on the Kickstarter page for the show called it "Starkid's New Musical", in which they just rolled with it).
"I hope you find that swimming pool" in Harry's repeat of "Going Back to Hogwarts" to his son was added last minute back stage. And all the better for it.
The whole rule about having to touch the diary to see/hear Voldemort was something Joe Walker improvised to justify why Hermione couldn't see or hear him (In the script this isn't mentioned at all and he just hides under a desk when she comes in, but since this was a staged reading, there was no desk and thus, no real place for him to hide). And rather than treat it as a throwaway improv, Darren chose to bring it up again, turning a dramatic confrontation into comedy gold.
