Junior repeatedly refers to Yang as "blondie". Barbara Dunkelman's screen name within the Rooster Teeth community (as well as her Twitter handle, Xbox Gamertag, etc) is BlawnDee.
Ozpin's hair colour is a shout out to Monty. Monty was originally going to voice the character until he decided his voice wasn't right for the part.
Jaune's symbol, a yellow, double crescent moon, could be a reference to his voice actor and RWBY writer Miles Luna, whose last name is literally Latin for "Moon".
This is not the first time Jen Brown has voiced a proficient warrior with green eyes and red hair in a ponytail (Pyrrha Nikos)
Ryan Haywood still has a habit of locking up animals as Peter Port.
Burnie and Joel return as two quirky cops like in the Pirating short.
The full version of "Red Like Roses Part II" turns out to be a duet between singer Casey Lee Williams and her mother Sandy Lee Casey. This leads to quite a bit of Reality Subtext in the song itself.
In volume 2 Yang makes an Incredibly Lame Pun, something her voice actress Barbara Dunkelman is infamous for. This could technically count as Ascended Fanon as fans already had her making Incredibly Lame Puns in fanfiction and fancomics as soon as Barbara was announced as her voice actor.
Monty Oum will be voicing Qrow; Ruby's old scythe teacher. He also voices Lie Ren.
Kerry makes a very brief appearance near the end of Episode 9. His only line? The noise Andrew is known for on the Internet Box.
He's also confirmed to be voicing Neptune, one of Sun's teammates.
Miles voices Jaune Arc.
Fan Nickname: Most of which are supplied by the wiki as placeholder names.
The fans used to refer to characters by their colors before their names were revealed. For example, Blake was Black and Weiss was, well, White. This carries on in a slightly different way later in the series, with the fandom using name colors from other languages as well.
Fans have been calling Junior's weapon the "Batzooka", saying he must have stolen it from Batman.
In the same video, we have DJ Deadb3ar.
Jaune will forever be referred to as Vomit Boy to some.
Before their names were revealed, Pyrrha was Umber, Nora was Apricot, and Ren was Nero. The first letters of their names, along with Jaune's, were meant to spell JAUN in the same way that Ruby, Weiss, Blake and Yang spelled RWBY. After their full names were revealed, ANVL became a short-lived placeholder, derived from their surnames: Arc, Nikos, Valkyrie and Lie (though Ren's surname is debatable). It was quickly replaced with JNPR (Jaune, Nora, Pyrrha, Ren) once Monty tweeted that it wasn't ANVL.
Continuing with weapons, Pyrrha's was called the Magnospear (derived from the word magnetosphere) and Xiflelin (portmanteau of xiphos, rifle, and javelin), Jaune's Sword and Shielth, Ren's Jade Dragons, and Nora's was Amethyst Thunder. Due to speculation of the importance of Jaune's weapon, it was often also referred to as Excalibur.
Roman Torchwick's weapon is often called Candy Cane.
Sun's bo staff/nunchucks/shotguns are referred to as Gunchaku.
Some of the techniques also get nicknames, such as Weiss's Air Step and Adam's OHK against the Spider Droid being called Seeing Red or Moonslice, the latter of which is based on a tweet from Monty with notes about what seems to be the Black Trailer.
Speaking of the Spider Droid, it and the Knight are still technically unofficial names.
The creature from the class in episode 9 captured by Professor Port was being called Edgar after a cow captured by Port's voice actor Ryan Haywood in Roosterteeth's Minecraft streams.
The two members of Team CRDL seen during the Initiation (Russel and Cardin) were referred to as Mohawk Guy and Armor Guy respectively.
Cinder is the witch that aids Roman in the first episode; fans like calling her Wicked Witch or Crimson.
The droids in the Black trailer are AK-130s. Due to the similarity in name to the AC-130 gunships - which are called "Spookies" - these droids are called such as well.
The Grimm creatures' names: Beobears (Ursa), Basilisks (King Taijitu), and Scorpius/Scorpi (Death Stalker).
Cardin's mace weapon is called Almace, or by others DoucheWhisk.
Team POGO: Professor Port; Ozpin; Glynda Goodwytch; and Professor Oobleck
Team QROW: Speculating the team up of Qrow, "Summer Rose", Ozpin, and Glynda Goodwitch... an alternative choice would be Roman in place of Rose.
Team Sloth seems to be a popular one on Deviantart and Tumblr.
Team Double-Date Night for JNPR due to how smoothly the two pairs ship.
Mercury's shotgun-greaves have gained the nickname Shoot-Boots in some circles of the fandom. Others have taken to calling them Talaria, after the sandals that the Roman God Mercury was said to wear.
Penny is suggested as being the daughter of Gepeddo.
Flip Flop of God: Sun's name was listed as Sun Wukon in the episode 16 credits, but it was Sun Wukong in the credits of episode 15. Presumably the G-less spelling is a typo, as other posts by Monty have used the G.
The Other Darrin: Visual example. The Beowolves were first introduced in the Red trailer, which Monty had been working on by himself. Later, they were redesigned by some of the concept artists and character designers.
Professor Ozpin was originally supposed to be voiced by Monty Oum himself. Matt Hullum also auditioned for the part, but it has been confirmed that he'll be voicing another character. Monty is voicing Lie Ren, but Matt's role hasn't been confirmed yet.
Gavin Free was originally slated to voice Junior. Though he was replaced by fellow Achievement Hunter Jack Pattillo, it has been confirmed he will play someone else in the series. This is somewhat humorous when one realizes the scene was originally Barbara putting Gavin's balls in a death grip. His signature scream probably would've been included, too. Given that Barbara and Gavin are one of the Rooster Teeth fandom's One True Pairing, the squees may have overwhelmed Gavin's scream somehow.
Many scrapped ideas regarding character design were shown on the panels at RTX 2013:
Ruby's hair was originally going to be gray, because Monty wanted to evoke a kind of wolf-like appearance for her. He mentioned later that Ruby's current hairstyle still looks kinda 'wolfy'. Her cape was also originally going to have a muff-like thing around her neck, but animation issues restricted that.
Both Ozpin and Glynda were going to have more cape elements in their design, but they were scrapped for the same reason as Ruby's cape-muff.
Roman Torchwick's early designs had a striped scarf.
Team RWBY wasn't supposed to have hair colors that matched their theme colors, and everyone but Yang was a brunette. So, Yang was the only one who ended up keeping her original hair color.
By the original plans, Jaune was actually on the right track in the cave in Players and Pieces, because the relics were going to be inside assorted Grimm, including the Deathstalker stinger.
Nora was originally meant to have a sash that wrapped around her waist, and ended in two long tails. Monty scrapped the idea because he thought it would be too hard to animate.
RWBY Volume 2: Production Diary 1 describes Velvet as simply having been created for the sole purpose for demonstrating the discrimination Faunus face, but fan response to her was so positive that she was further written into the story for Volume 2.
Kerry: It's a good thing we didn't go-we almost went with a dude with an elephant trunk. Probably wouldn't have turned out— Miles and Kerry: Not as good.
Early art for Ren implies that he was originally intended to be a more androgynous or even female character wielding a sword.
Similarly, early art for Blake gave her heterochromia and two differently colored cat ears.
Monty's earliest doodles of Yang, Pyrrha and Weiss and show some minor differences. Yang's pants and some highlights of her clothes were yellow and she had a different style belt. Pyrrha had some armor covering her sash instead of a belt, extra armor on one leg, and no tiara or ponytail. Weiss' clothes weren't as detailed, her jacket lacked it's red collar, is missing her black undershirt and had a different ponytail. Also, it shows a few early designs for her snowflake emblem.
Cinder at one point had incredibly long, flowing sleeves similar to Weiss.
He seemed very fond of the Nora mafia princess theory.
Though many had assumed that the Faunus were inspired by the many animal characters that exist in anime, Monty Oum has revealed that they actually stem from his love of the old Hanna-Barbera cartoon Snagglepuss. (This is probably Trolling Creator).