So despite the advertisements and cover showing Marv with blonde hair, this story shows us that Carol has been sent into the Negative Zone, and meets Marv at a time shortly after he was blasted into the negative zone and before he gained cosmic awareness.
Despite the fact that Marv appeared to be wearing Nega bands, he referenced his attacks as coming from his old Kree Unibeam, the weapon he had back when he was in his old green/white Kree uniform, a weapon that was abandoned after he gained the Nega Bands.
Also despite wearing the nega bands, Marv borrowed an alien jet belt for flight, when at this point he should have been able to fly without such technology due to the bands.
This is clearly shortly after he was linked to Rick because when Marv recaps his life we do see a scene of him saving Carol from the exploding Kree device that empowered her. So he should have been flying and blasting with the power of the nega bands, not a jet belt and not a unibeam.
Also the nega bands were supposed to stay on the wrists of whomever was on Earth at the time, Rick or Marv. The one in the negative zone was not supposed to have them so drawing Marv with nega bands at all was an error, much less that he wasn't using their power.
Also Marv's speech patterns at times were off, even one time he was talking like Yoda! UGH.
Anyway after they defeat Annihilus, they are chatting for a bit and Carol decides to tell him who she is, Carol Danvers. However as she starts to refer to him by his old Dr. Lawson alias she does teh big fade and disappears back to her proper timeline. Marv bids her farewell, not realizing that it was a future version of his friend and almost girlfriend Carol Danvers.
I did like the little easter egg/joke about how the aliens mispronounced Carol as Car-ell, just like when Marv first appeared on Earth and people heard the name Mar-Vell and thought it was pronounced Marvel.
and OF COURSE Carol doesn't even THINK OF TRYING TO WARN MAR-VELL about an impending future fight with Nitro and the NERVE GAS that would sicken and kill him!!!!!!!!!!!!!!!!
SO, all in all, while Carol may have gotten a life lesson or two, Mar-Vell's powers and character were inaccurately portrayed and of course Carol doesn't make an effort to try to change his fate by warning him.
In the end, another stupid Generations issue.
It also kind of disgusted me that Mar-Vell had no clue who Carol was. First thing out of his mouth, imo, should have been, "Carol! You've got powers like mine!"