At the 2011 San Diego Comic Con, it was confirmed that Clark Gregg would provide the voice of S.H.I.E.L.D. Agent Phil Coulson, the same character Gregg has played in the Marvel Cinematic Universe movies released by Marvel Studios, including both Iron Man (2008) movies, Thor (2011), The Avengers (2012) and agents of shield(2013)
When the show was renewed for a 4th season of 26 episodes that brought the total episode count to 104 episodes. This makes Ultimate Spider-Man, not only the longest running Spider-Man series (surpassing the 90's animated Spider-Man which ran for 65 episodes), but also the longest runnning series ever based off a Marvel comic (surpassing the 90's animated X-Men which ran for 76 episodes). It's even the longest running show Marvel has ever been associated with surpassing 80's shows like G.I. Joe and The Transformers (which ran for 95 and 98 episodes respectively).
At the 2011 San Diego Comic Con, The Avengers were confirmed as guest-stars on "Ultimate Spider-Man", including Iron Man, Thor, Captain America, and The Incredible Hulk. This will be the first time that Spider-Man has teamed on-screen with The Avengers in an animated series since 2010's The Avengers: Earth's Mightiest Heroes and the first time Spider-Man and the Hulk have been on the same animated series since 1981's "Spider-Man and His Amazing Friends".
The trivia items below may give away important plot points.
This is the first Spider-Man animated series in which Aunt May knows Peter is secretly Spider-Man, it turns out she knew right from the beginning, but we, the audience, don't learn this until the Season 3 finale.