When it was announced in the summer of 2011 that both NBC and ABC were developing television shows based on the classic fairy tales, an immediate rivalry between Grimm and Once Upon a Time was assumed to occur by the media. After both shows premiered it became quickly obvious that tonally they were radically different shows.
The CW's Supernatural is a better match against Grimm. They are tonally and serially similar, sharing the same audience and even the same time slot in Grimm's first season before Supernatural changed nights the year after.
Fan Nickname: Captain Renard aka "Captain No Pants." To be fair, Sasha himself started it in response to David's (Nick) shirtless scenes during a friendly challenge on who could get the most twitter followers.
Hide Your Pregnancy: Bree Turner who plays Rosalee was pregnant during season 2 and had to conceal her belly.
I Knew It!: A lot of people had speculated that Nick and Trubel were related, because of the strong resemblance between the actors. Come the series finale, one of the last lines of dialogue on the whole show casually mentions that Trubel is Nick's third cousin on his mother's side.
Promoted Fanboy: Jacqueline Toboni, the actress who plays Trubel, was originally a University of Michigan student who was a huge fan of the series.
Screwed by the Network: The show bounced around the schedule in its early seasons until NBC execs saw that it was bringing in the same solid audience no matter when they put it. Realizing that they had a solid performer on their hands (a true rarity in the modern NBC lineup), they placed it in its current Friday night slot and started trying to build a horror block around it.
After the end of the Season 3 episode "The Wild Hunt", the screen fades to black to reveal the words: Oh $(*@&. The best part was that this was aired right before the 2014 Winter Olympics, so viewers have to wait almost an entire month for the next part.
The production crew threw in the scene where Sean is critically wounded in "Blonde Ambition" due to Sasha's contract negotiations. They also wanted to see the reaction of Sasha's fanbase on how many would throw a fit if the actor would leave, due to his shirtless scenes.
Russell Hornsby, the actor who plays Hank, sustained a serious foot injury during Season 2. Naturally, there's no way to work around this on a cop show, so instead they sent Hank on vacation for an episode and had him return with a similar injury.
During the fourth season of "Grimm", actress Claire Coffee (Adalind Schade) became pregnant with her first child. This was particularly amusing because her character, Adalind, had just finished a pregnancy arc. The writers decided to write the pregnancy in, leading the characters to exclaim an exasperated "Again?!" when Adalind reveals her pregnancy.