Secret Wars, Chapter 1: Arrival - S5-E9
Other mistake: When Spider-Man is scrolling through his options of which member of the X-Men that he can teleport to the planet, the picture of Cyclops shows part of his yellow "bandolier" colored blue.
The Return of Hydro-Man: Part 1 - S5-E7
Other mistake: When Spider-Man catches up to Mary Jane and Hydro-Man at the foundry, he webs up Hydro-Man's left wrist. When the shot changes to Spider-Man landing, he is not holding onto the web-line. When the shot changes back to Hydro-Man, his arm his pulled with the web-line remaining taut, even though Spider-Man is not holding the web. If Hydro-Man was moving his arm on his own, then the web-line would be slack.
The Return of Hydro-Man: Part 1 - S5-E7
Other mistake: When Spider-Man breaks the chain off the steering wheel of the boat, several of the links on the back loop of the chain break off, which would be impossible since he broke the chain at the front.
Six Forgotten Warriors Chapter 5: The Price of Heroism - S5-E6
Other mistake: Two scenes in this episode are shown out of order. First we see Captain America and Spider-Man lying on the ground near the dimensional vortex at the mercy of Chameleon and the Red Skull, with Cap flicking a rock across the room to distract Chameleon so that he and Spider-Man can re-engage them in battle. Shortly after, we see Spidey and Cap arriving at the dimensional vortex to configure it to defeat Electro, with Chameleon and Red Skull attacking them once Spidey has finished with the vortex, revealing they had been lying in wait knowing full well someone would figure out that the vortex was the key to stopping Electro.
Six Forgotten Warriors Chapter 5: The Price of Heroism - S5-E6
Other mistake: When Spider-Man and Silver Sable are chasing the Red Skull and Kragov, they are able to deduce which direction they are going by identifying their footprints. However, Spidey and Silver Sable themselves don't leave footprints when walking over the same spot.
Six Forgotten Warriors Chapter 2: Unclaimed Legacy - S5-E3
Other mistake: When Silver Sable infiltrates Kingpin's Russian lair with sleeping gas, before falling unconscious, Kingpin correctly deduces that he has been betrayed. In the next scene, Kingpin asks Silver Sable how she was able to infiltrate his lair, and she tells him one of his men is a traitor, which elicits an incredulous reaction from Kingpin, completely contradicting the previous scene where Kingpin already surmised there was a traitor.
The Wedding - S5-E1
Other mistake: When J. Jonah Jameson is on the phone with Wilson Fisk, one shot shows that the area of Jameson's desk between the receiver and the cord is colored the same gray color as the cord, instead of the golden-brown color the rest of the desk is.
Six Forgotten Warriors Chapter 4: The Six Fight Again - S5-E5
Other mistake: The news footage of the elderly Six American Heroes being attacked by the Insidious Six is merely clips from the previous episode.
Sins of the Fathers Chapter 8: The Ultimate Slayer - S3-E8
Other mistake: When Kingpin is berating Smythe over his failure to kill Spider-Man, the camera footage Kingpin is showing of Spider-Man is merely clips from previous episodes.
Neogenic Nightmare Chapter 7: Enter the Punisher - S2-E7
Other mistake: Spider-Man and Detective Lee both comment on the skull on the Punisher's shirt when they first see him. However, the Punisher is wearing body armor that covers most of his chest and abdomen in this scene, so there's no way they would know that he has a skull on his shirt.
Other mistake: Spider-Man is shown web-slinging past several glass buildings, but he does not cast a reflection in any of them. (00:00:10)
The Alien Costume: Part 1 - S1-E8
Other mistake: After tricking police by disguising himself as a policeman, Spider-Man changes his clothes in the middle of traffic with numerous people around but somehow nobody notices this.
Neogenic Nightmare Chapter 8: Duel of the Hunters - S2-E8
Other mistake: After falling down the cliff and getting blasted back by his van's explosion, the Punisher shows no signs of injury. This kind of fall combined with explosion should have killed him, or at least injure him very severely, as he is a normal human without any superpowers.
Other mistake: Despite being Shield agents the guys shown in the target practice room wear the same uniforms as the guards working for The Kingpin.
Secret Wars, Chapter 3: Doom - S5-E11
Other mistake: This series is in the same continuity as the other Marvel animated series from around the same time - X-Men, The Incredible Hulk, Iron Man, and Fantastic Four - by virtue of each aforementioned show crossing over with at least one of the others. However, in Fantastic Four, Dr. Doom had a German accent, and in this episode he has a Russian accent.
Partners in Danger Chapter 5: Partners - S4-E5
Other mistake: When baby Silvermane is secured to the platform, his arms are long enough to reach inside the restraints. Considering he is physically a baby, the mistake is that the animators either goofed and drew him to be a little older, or that his arms are disproportionately long.
Suggested correction: It was a part of the character's redesign. The writer of Spider-Man, John Semper Jr, disliked the Fantastic Four cartoon to the point that he not only changed characters' designs but their voice actors as well.
Redesigning the character is not a valid correction, because it still creates a contradiction within the shared universe. Even under the pretense of redesigning the character due to not liking the previously established version, it would still be a deliberate mistake.
Phaneron ★