Absentee Actor: Lloyd has pretty frequently been absent as a rapper, though any time this is the case, he'll still pop up in the background playing a non-participant such as Carl Sagan or John McCain. Peter, meanwhile, had taken part in every battle without fail all the way up until Cleopatra vs. Marilyn Monroe, where both Lloyd and Peter played cameo roles. (The fact that this is the first time Peter didn't rap is significant when you consider that this wasn't even the first woman vs. woman battle...)
Bruce Lee vs. Clint Eastwood is notably the first battle where Lloyd rapped but Peter didn't. Since then, we've also had Adam vs. Eve, Goku vs. Superman and Jack the Ripper vs. Hannibal Lecter.
Tesla vs. Edison is a weird example in that it's the only battle where Peter is visually completely absent but still does the vocals for Tesla.
Michael Jordan VS Muhammad Ali is the first battle ever where neither Peter nor Lloyd appear at all - not for vocalsnote Though Peter still voiced the announcer, not for a cameo, nothing.
Similarly, Edgar Allan Poe vs Stephen King, which also pits two returning guest stars (Zach Sherwin and George Watsky) against each other.
"Renaissance Artists vs the Teenage Mutant Ninja Turtles" puts a new twist on this, with Peter and Lloyd voicing the Turtles. Lloyd performed as the turtles along with stunt actor Xin Wuku, so he wasn't entirely absentee. The battle also brought in a record four special guests (previous guests Rhett & Link and first-timers Ian and Anthony from Smosh) as the Renaissance artists.
Acting for Two: Sometimes the actors would play more than 1 character in one video.
Nice Peter plays both Spielberg and Michael Bay in the Steven Spielberg vs. Alfred Hitchcock battle.
In the Rasputin vs. Stalin video, Peter plays three people: Rasputin, Lenin and Putin; while Stalin and Gorbachev are both played by EpicLloyd.
Taken Up to Eleven (well, more like fifteen) in "Wonder Woman vs Stevie Wonder" when Lilly Singh and a massive array of wigs and tops play all of Steve's nine different kids AND their five different mothers.
The Cat in the Hat wears sunglasses identical to Nice Peter's signature look. His voice is also the same.
May or may not have been intentional, but the Wright Bros., who launched their first plane in North Carolina, are played by Rhett & Link who were both born in said state.note Probably intentional, otherwise they wouldn't have "Representing North Carolina" in one of their verses.
NicePeter plays Albus Dumbledore in the eleventh battle, where he finishes his last verse with "Imma fly like it's Quidditch". This was the chorus of one of NicePeter's own non-rap battle songs.
The 10th Doctor calls Doc Brown "the wannabe Einstein minus the 'stache". MC Mr Napkins played both Einstein and Brown.
Bruce Lee tells Clint Eastwood that he "fucked up Chuck Norris". Both Eastwood and Norris were played by EpicLLOYD.
Moses is seen with smoke coming from his mouth, and even directly references some of Snoop Dogg's earlier lyrics in his verses.
Performers reprising characters played in their earlier works is not without precedent: Lisa Nova as Sarah Palin, NicePeter as Santa Claus (accompanied by an EpicLloyd elf), Dante Cimadamore as Nikola Tesla, and numerous videos of Alphacat as Barack Obama all predate their portrayal in the Epic Rap Battles.
Another ambiguously intentional one; Sir Issac Newton, played by "Weird Al" Yankovic in his second verse tells Bill Nye he can "calculate the weight, the size, and the shape of the shadow of the mind [Nye is] standing in" may be referencing "My shadow weighs 42 pounds" from Al's song, "Fat".
George Watsky, who gets one blazing fast rap verse per appearance and can rap in both iambic pentameter and trochaic octameter.
Hitler vs Vader 3 gives EpicLloyd an opportunity to remind everyone that he did gymnastics in college.
KRNFX is an accomplished beatboxer, which comes in handy when Lao Tzu supports Confucius during the Eastern Philosophers' second verse.
Cast the Expert: Happens with both characters in "Bruce Banner vs Bruce Jenner" after their transformations: The Hulk is played by bodybuilder Mike O'Hearn, and Caitlyn Jenner is played by transgender rapper No Shame.
Casting Gag: Lilly Singh, a.k.a. II Superwoman II, is cast as Wonder Woman, though she admits in the Behind the Scenes that she doesn't know much about Wonder Woman. She apparently found out from the rap lyrics of how Diana was made from clay.
Dyeing for Your Art: NicePeter had his barber take in his hairline so he could play Steve Jobs. Since his barber wasn't happy with doing it, he was generous, so NicePeter went back and made him do it worse.
Fake Nationality: Almost every rapper so far has been American, playing British guys, Germans, Italians, the list goes on.
Mike Diva (Bruce Lee's actor in Bruce Lee VS Clint Eastwood) lampshades this by stating that he sucks at Asian accents, so Lloyd and Peter had to coach him. Pete then proceeds to walk by and claim no involvement in said accent coaching.
An example that doesn't extend to rappers. PewDiePie cameos as the Russian Mikhail Barishnikov, though he is actually Swedish.
Dan Bull averts this, as he's a Brit playing Jack the Ripper.
In Eastern Philosophers VS Western Philosophers, the Chinese Sun Tzu and Laozi are played by Timothy DeLaGhetto (whose parents immigrated from Thailand) and KRNFX (of South Korean descent), respectively. MC Jin, who plays Confucius, actually is of Chinese descent, however, making him an aversion.
Fan Nickname: "Astrophysics Black Guy" for Neil deGrasse Tyson.
Fandom Nod: The basis for the rap battle, as it is the viewers who decide what comes next. At the end of most episodes, the YouTube comments that suggested the match-up are shown. There were at least three requests for Elvis Presley vs. Michael Jackson; one had over one hundred likes, and all three were acknowledged at the end of the respective video.
Averted with Ben Atha as James Bond while played straight with both Peter and Lloyd as Austin Powers and old-school Bond.
Genius Bonus: Nietzsche going absolutely ballistic at the end of his last verse is this. Confucius said the Nazis were inspired by his work. However, Nietzsche was vehemently against antisemitism, proof being letters he wrote to his sister, where he lambasted her for her backwards views on the Jews. Also, that very same sister reappropriated his work for the Nazi cause.
Only one day after the release of Donald Trump vs. Ebeneezer Scrooge, Donald Trump tweeted about the video, understandably confused and asking "Whats up with this rap stuff with me and Ebeneezer Scrooge?" ERB wasted no time in acknowledging that Trump acknowledged ERB.
ERB News Season 3.5 directly states that Obama saw the rap battle between him and Romney. NicePeter and Alphacat even got invited to take part in a White House panel on health care.
Never Work with Children or Animals: The BTS for Bob Ross vs Picasso implies that they were originally going to pan down to Bob (the wiener dog playing Lump) when Picasso mentioned him, but couldn't get Bob to stay still long enough to pull it off.
Lloyd as Picasso: *chasing after Bob* He's too fast!
Old Shame: While he isn't upset with how the battles turned out, EpicLLOYD understandably felt uncomfortable with playing Adolf Hitler.
ERB typically releases a battle once a month, but during the Summer 2012, there was a three-month hiatus. Teddy Roosevelt called them out on it and threatened to whoop some ass. To make up for lost time, new battles premiered every other Monday right up until the week of Christmas, and then picked up again in February.
Season 4 fell victim to this as well. Beginning in mid-December, it was announced that new battles wouldn't air until May 5th. It wasn't until May 25 that the next video actually came out.
Season 5 has also suffered from this, albeit to a lesser extent; while it hasn't been prone to a massive hiatus like previous seasons, nearly every individual battle has been uploaded a day later than intended.
Scully Box: The BTS for "Renaissance Artists vs the TMNT" reveals that a row of these were needed to help Ian, Anthony and Link measure up to Rhett.
So My Kids Can Watch: Unknowingly invoked - Chali 2na didn't quite get the impact left by Epic Rap Battles of History until he brought it up to his son, who didn't care that his dad wouldn't be able to go out with him for a movie!
Throw It In: They made a demo for the Napoleon VS Napoleon battle that eventually got redone, but they used the original for the behind the scenes video for the same battle.
In Genghis Khan VS The Easter Bunny, there's a part where Lloyd (playing Khan) smashes a chocolate egg with his sword. The behind the scenes video shows that they didn't think the idea would actually work, so they only did one try before moving on. Since Lloyd actually hit the egg on his first try (which people were not expecting), they decided to put it in.
Torch the Franchise and Run: Adolf Hitler VS Darth Vader 3 evidently will be the last match between those characters. The reason for this is clear in-universe: Darth Vader cuts Adolf Hitler in half, and it's implied that his remains land in the Sarlaac pit. Aside from story purposes, there's also the inclusion of a comment in the video that states that the match-ups between these characters are getting stale, which would imply that the crew behind the show are getting a little sick of it. Further confirmed by the Season 4 announcement trailer, which shows Hitler's ghost being captured by the Ghostbusters.
More like "Torch The Running Gag And Run", but The Stinger for the Rick Grimes vs Walter White BTS video has the "zombies" holding a mock funeral for the Heroin Joke, implying that we might never hear it again.
Christopher Columbus' original opponent was Neil Armstrong.
The lyrics for Bill Gates vs. Steve Jobs match originally included a line about how Steve's ailment was the only PC he couldn't beat. They decided to not use it because it didn't flow as well and crossed well into Too Soon territory.
Walked into the record industry and killed it
Got fired from my own company, rebuilt it
My legacy will never fall
But a PC got me after all
There was a battle between Hillary Clinton and King Henry VIII in the works, but it got canned due to dissatisfaction with the recording track.
Mikhail Gorbachev's iconic crimson birthmark was originally going to spell out "ERB". Lloyd didn't really like the idea - mostly because it was impossible to see without tilting his head absurdly - so they settled with the birthmark's actual look.
According to the behind the scenes, Peter, who cameoed as Steve, wasn't planned to appear at first, which would have made this the first battle where he would not be in at all.
Maximillian of Assist Me made a parody of this series called "Epic Rap Battles of MvC3" between Albert Wesker and Doctor Doom. He was going to make more, but the Epic Rap Battle people sent him a Cease And Desist, basically saying "this one's okay, but if you make more, you'll hear from our lawyers." (No, they don't mean Phoenix Wright...)
The BTS for Miley Cyrus vs Joan of Arc shows a hanging rope prop that most likely was intended for a "Wrecking Ball" reference. They also went over possible lines for Peter and Lloyd's cameo as Miley and Lilly. Neither of these are in the final cut.
Blackbeard's other opponents considered for the battle were Jack Sparrow and Cap'n Crunch before deciding on Al Capone, who, possibly intentionally, references both Jack and Cap'n in his first two lines.
The BTS gives two other lines that were considered for Al Capone's jab at Blackbeard's beard.
Peter: What beard joke do you like better: "From the likes of you, I've got nothing to fear/'cept maybe the evil beasties you've got nested in your beard." or "That rat's nest of a beard's trapped so many crumbs/you could feed your grubby crew lunch for a month."?
Peter originally wanted Smosh to portray Bill and Ted, but they disliked the idea.
Peter makes a comment about Hitler and Vader never being able to settle their differences in the Season 3 Opener behind-the-scenes video, so there's a likely possibility that they will show up yet again if/when season 4 comes out. Though Peter did confirm that he's tired of Hitler vs. Vader.
As of season 4's release it's been confirmed, that Hitler vs. Vader is done.
They've confirmed that they're not interested in making Homer Simpson versus Peter Griffin as it just sounds too boring. Similarly, they won't do Tobuscus versus Pewdiepie, as they love both of them and are unsure as to how it would work. Many times, a rap battle between Obama and Osama bin Laden has also been ruled out, though Obama later appeared rapping against Mitt Romney. They've also stated they will never have Steve Irwin appear (despite him being a popular request), because they're afraid of it falling into Dude, Not Funny!.
Three of the matchups have been done before by more violent shows. Superman vs. Goku note And the rematch and Robocop vs. Terminator were done by Death Battle, while Steven Spielberg vs. Alfred Hitchcock has been done by Celebrity Deathmatch.
There have been four instances of both a character and their creator having both appeared in separate rap battles: HAL 9000 and Stanley Kubrick, William Shakespeare and Romeo & Juliet, Gandalf and J.R.R. Tolkien, and Stan Lee and The Incredible Hulk (Stan Lee created Marvel's Thor but the Thor in ERBOH is not explicitly stated to be him (aside from a brief MCU nod) and Deadpool, although owned by Marvel, was not created by Lee). Steven Spielberg was involved in Back to the Future where Doc Brown originates from, but he was a creation of Robert Zemeckis.
Star Wars, Marvel Comics, and DC Comics are the only franchises with two characters who battled (Darth Vader and Boba Fett for Star Wars, Deadpool and the Hulk for Marvel, and Batman and Superman for DC). As of "Wonder Woman vs Stevie Wonder", DC officially beats out both Disney properties and has its iconic "Big Three" all represented!