The Origin of the Fantastic Four: Part 1 - S1-E1
Other mistake: When Puppet Master is making a clay figurine of Thing, the mold he uses doesn't have a Thing-shaped interior with which to make a detailed figurine. The figurine should have just looked like an undefined human-shaped figure. (00:15:20)
To Battle the Living Planet - S2-E6
Other mistake: This series is in the same continuity as the other Marvel animated series that aired around the same time - X-Men, Spider-Man, Iron Man, and The Incredible Hulk - by virtue of each aforementioned show crossing over with at least one of the others. However, early in this episode, the Fantastic Four receive help from the Avengers, and two of their members are Iron Man and She-Hulk. Iron Man is not a member of the Avengers in this universe, he is a member of Force Works. She-Hulk is not a member of the Avengers either. She is an attorney and is also frequently off doing missions with Bruce Banner/Hulk. (00:01:52)
Other mistake: This series is in the same continuity as the other Marvel animated series that aired around the same time - X-Men, Spider-Man, Iron Man, and The Incredible Hulk - by virtue of each aforementioned show crossing over with at least one of the others. However, the cameo appearance by Scarlet Spider in this episode creates a contradiction with Spider-Man, as in that series, Scarlet Spider was an alternate - and possibly cloned - version of Spider-Man from a different reality, who never visited the reality that this and the other Marvel shows take place in. (00:09:31)
Other mistake: When Dr. Doom's attendant is removing the wrapping from his left hand, in the first shot, he is simply holding onto the wrapping and moving his hand back and forth. (00:05:42)
Prey of the Black Panther - S2-E7
Other mistake: When Reed is looking at Africa on his radar, the continent is too crudely drawn to be a legitimate radar image. (00:05:52)
Other mistake: When Johnny is asking Rick Jones where Dr. Banner is, he pulls up the sleeve of his glove to look at the time on his watch. However, there is no bulge on his wrist to indicate he is wearing a watch under the glove in the first place. (00:12:29)
And a Blind Man Shall Lead Them - S2-E1
Other mistake: When the detonator in the elevator is counting down from 15 seconds, it counts down at a consistent rate until it goes from 6 to 5, in which case it takes about twice as long as the other intervals. (00:15:36)
Behold the Negative Zone - S1-E12
Other mistake: When the heroes are looking over the footage of their fight with Annihilus, Reed has been drawn twice. He is both at the control panel, and behind himself and to the right. The one that is not at the control panel was meant to be Johnny. (00:10:01)
The Silver Surfer & the Return of Galactus - S1-E13
Other mistake: When Reed punches the dinosaur, he transforms his hands into what looks like the end of a sledgehammer. While Reed can change the shape of his hands with his stretching ability, he does not have the power to change the color of his skin in the process. (00:03:57)
Other mistake: When Alicia takes the grape soda out of the fridge, she pours it into her cup without first opening the can. If the can was already opened, then its contents would have spilled out from oscillation when Thing was dancing with the fridge before he set it down. (00:03:05)
The Mask of Doom: Part 2 - S1-E9
Other mistake: When Johnny is rapidly spinning to cause an updraft, an overhead shot shows the rapid movement of his arms to be both in his Human Torch form, and in his costumed form. (00:12:08)
The Mask of Doom: Part 2 - S1-E9
Other mistake: When the ski patrol is looking down at what they believe to be the dead bodies of the Von Dooms, one patrol member has some scruff around his chin that disappears when he smiles. (00:07:36)
The Mask of Doom: Part 2 - S1-E9
Other mistake: When Reed turns around and sees the huge spiked ball rolling towards him, Johnny and Thing, you can see that it is only a few dozen feet away from them at most, and is rolling towards them rapidly. Despite this, it takes more than 20 seconds for it to reach where they were standing. (00:05:00 - 00:05:23)
The Mask of Doom: Part 1 - S1-E8
Other mistake: After Johnny frees Reed from his containment bubble, Reed stretches himself out of it, and Johnny can be seen hovering above and behind him in the background. Despite being in the background, Johnny's left knee somehow appears in front of Reed's body. (00:19:03)
The Mask of Doom: Part 1 - S1-E8
Other mistake: Reed tells Johnny to push the timer button on his watch to activate the cutting torch. However, the torch is activated without Johnny ever pressing the button. (00:17:59)
Superskrull - S1-E7
Other mistake: When Manny Friendly is entering the Fantastic Four's lab, he is running in place for several steps. (00:15:49)
The Silver Surfer & the Coming of Galactus: Part 2 - S1-E6
Other mistake: When Alicia is noting the weariness in Silver Surfer's voice, her piano is missing its black keys. (00:07:01)
Answer: Gleaned from the Internet: Much of the negative reaction was due to the poor, simplistic, and outdated quality of the animation where the characters moved stiffly and clumsily through scenes. There were also some obvious animation compositing gaffs. The animation colors were also criticized as being overly bright and cheery and out of character to the established story's darker tone. The broad humor of the first season was replaced by a more mature narrative between the characters.
raywest ★