Plot hole: Vulture was able to re-create his suit despite the tech for it being confiscated when he was arrested. Also, the tech does not exist in the Venomverse, so he would have had no means of accessing it by any stretch of the imagination.
Plot hole: It appeared there was ample time for Milo to apply the so much desired 'cure' that Michael warned him about. Milo is no doctor and did not witness Michael's application procedure. Milo could have never known the precise way to perform the risky procedure, let alone he had assistance from anyone other than Martine.
Plot hole: Vulture from the MCU is pulled into the Venomverse due to the spell cast by Doctor Strange in No Way Home. This is absurd. The first spell pulled characters from other universes into the MCU, while the second spell brought the characters back to their proper universes. Neither of these spells involved pulling characters out of the MCU and into the other universes. Vulture of the MCU was already in his proper universe. No explanation is provided for this.
Continuity mistake: There were only two serums left after Morbius took his. Milo takes one and kills the nurse. The next morning when Michael thinks he had killed the nurse he goes to grab a bunch of blood and make a run for it. There are still two serums, even though Milo has supposedly already taken one of the remaining 2.
Factual error: When Martine enters the passcode to reveal the bats, you see her hit "3" first followed by what seems to be "5" (the rest is blocked by her body). She then tells Michael his passcode is the first 6 digits of pi backwards. The first 6 digits backwards would be "951413."
Character mistake: Doctor Bancroft mispronounces "Nobel" when reading the headlines to Michael. She pronounces as "noble." It's a famous award, especially in the field of science and someone as smart as she is suppose up be would know how to say the name.
Suggested correction: Honestly, I just rewatched the scene in question, and I really wouldn't consider that a character mistake. It's not a super egregious mispronunciation to begin with (the difference between the sound of the words is quite minor), and based on the way she speaks and the fact she has a bit of an accent, it just seems like more of a personal affectation than a character mistake.
Continuity mistake: At the beginning of the flashback in Greece, the pieces on and around the chessboard change. When we first see the board, most of the white pieces are on the back row, and then we see 2 pawns removed. In the next shot, when the king is knocked over, some of the white pieces on the back row have moved and there're several pieces that have been removed.
Factual error: During the ship scene, the computer graphic of splicing bat DNA into human DNA is wrong. DNA strands are complementary to each other. If you remove a segment from one side, what you can put back is predetermined by the other side, regardless of the source (bat, elephant, fish, etc). The graphic should have shown both sides of human DNA replaced (or just added) by both sides of bat DNA. As it is in the movie, the injection should not have any anatomic/physiologic effect.
Suggested correction: If you look it's been clear that Strange's spell wasn't perfect. Eddie being brought into the MCU when he had no idea who Spider-man was...nor did he die. Electro's new-look and having no idea who Spider-man was. If anything Clea, in MOM basically said he messed up. So that last spell didn't fix things. It's clear this is what they are building towards. Nothing is fixed. Either way it isn't a plot hole for this movie. Post credit scenes are usually teases for other movies to explain.