Tom Kenny voices Doc Ock, Wizard, Curt Connors (before "The Iron Octopus") and Vulture. "Iron Vulture" even has frequent banter between Ock and Vulture.
Tara Strong voices Mary Jane and Thundra. There's even a brief exchange of dialogue between MJ and Thundra during the pilot.
Matt Lanter voices Flash Thompson and Harry Osborn. The episode "Anti-Venom" milks this trope for all its worth, similar to "Iron Vulture" with Tom Kenny.
Trevor Devall fills in as Rocket Raccoon from "The Return of the Guardians of the Galaxy", onward in his own series.
After being voiced by Jack Coleman in the first and third seasons, Liam O'Brien took over as Doctor Strange beginning in the fourth season, also taking over the role in Avengers Assemble for its third season.
Season 4 sees Eric Bauza and Ogie Banks replace Dante Basco and Donald Glover as Scorpion and Miles Morales.
Out of Order: While not as bad as one of its predecessors , this trope has taken affect at times. For example, in production order, the last 6 episodes of season 3 are the Halloween episode, the Christmas episode, and the 4 part Contest Of Champions finale. The former two aired on October and December 2014, while the finale aired in October 2015, over 10 months later, with episodes taking place before the Halloween episode airing between the Christmas episode and the finale.
Recursive Adaptation: The show has a comic adaptation called Marvel Universe: Ultimate Spider-Man that started in April 2012.
Recycled Script: Both Freaky and The Incredible Spider-Hulk involve Spider-Man's mind getting swapped with that of another superhero's; Wolverine in the first episode, the Hulk in the second. Both times it's due to Mesmero, and someone else - Sabretooth and the Thing - attacks Spider-Man, adding extra complications.
Leo Fitz and Jemma Simmons are voiced by Iain De Caestecker and Elizabeth Henstridge, the actors who played them on Agents of S.H.I.E.L.D..
The episode "Flight of the Iron Spider" ended with the Living Laser ending up in the universe of The Superhero Squad Show and being attacked by the Super Hero Squad incarnation of Thor. The scene had Dave Boat reprise his role as Thor from that show (itself another case of this, as he first voiced Thor in the Ultimate Avengers duology).
Though initially voiced by Tom Kenny, starting with "The Iron Octopus", Dee Bradley Baker reprises the role of Curt Connors/The Lizard from The Spectacular Spider-Man. He likewise returns to voice Carnage.
In "Return to the Spider-Verse: Part 2", Seth Green reprises his role of Howard the Duck from Guardians of the Galaxy (2014).
In season 4, Ogie Banks reprises his Marvel Heroes role as Miles Morales.
In the French dub, Nick Fury, Hulk, and Thor are voiced by Erwin Grünspan, Claudio Dos Santos, and Mathieu Moreau respectively, all of them reprising their roles from The Avengers: Earth's Mightiest Heroes. Also, Wolverine is voiced by Robert Dubois, reprising his role from X-Men: Evolution.
An early promo poster showed Shroud (the costumed identity used by Kitty Pryde in the Ultimate Spider-Man comics) as part of the team instead of White Tiger.
about working with Drake Bell, as the actor was more focused on his phone and created an uncomfortable tension in the studio.