Warning: The following contains SPOILERS for Avengers: Endgame!
Avengers: Endgame truly lived up to its billing as the culmination of the Marvel Cinematic Universe to this point, providing plenty of callbacks and many surprising cameos. Perhaps most surprising among those cameos was Natalie Portman as Dr. Jane Foster, who hasn’t been seen in the MCU since 2013’s Thor: The Dark World. However, this cameo was not all it appeared to be, as directors Joe and Anthony Russo explained:
Anthony: All she did new for this movie was-
Joe: The voice.
Anthony: A little bit of voice-over when she’s talking in the distance, that’s it.
Although we see Natalie Portman as Jane Foster in Avengers: Endgame, she didn’t actually show up to play the character again. Her appearance in the film was just old footage left over from Thor: The Dark World that was repurposed for the movie; the actress didn’t film any new scenes. She did, however, provide some voiceover for Avengers: Endgame, as the Russo’s told Entertainment Weekly.
In the film, there are shots of Jane Foster in the distance with some Asgardians, and Natalie Portman recorded voiceover of her character thanking them for taking care of her. It’s not easy to even hear what she’s saying, but it adds some background to the scene, showing that this is all happening in a living, breathing place. It’s also nice to know that it’s actually Natalie Portman’s voice we’re hearing.
Natalie Portman had indicated in the past that she believed she was done with the MCU; she didn't appear in Thor: Ragnarok and given reports that she was not happy with the situation that led to Patty Jenkins leaving as director of Thor: The Dark World, it seemed unlikely she’d ever be in a Marvel movie again.
So when Natalie Portman showed up to the premiere of Avengers: Endgame, fans wondered whether or not the actress had returned to the fold and if the long absent Jane Foster would be in the movie. It turns out she did and she was, just not in any major way.
In Avengers: Endgame, the shot where Jane gets up from her bed and Rocket Raccoon goes after her to extract the Aether off-screen was framed rather oddly. And since we didn’t see her and Rocket or her and Thor together, I think many of us assumed that Natalie Portman didn’t really film any new scenes and her appearance was either old footage or digital wizardry.
It would have been nice for her to actually see Thor again to close out that story, especially given that she survived the snap and how he was weeping over her in the Time Heist prep meeting. But it’s better than nothing, and Thor didn’t want to be there and probably didn’t want Jane to see him in his dilapidated state.
Thor did, however, see his mother Frigga in one of the film’s more emotional moments. She died before the Decimation and he was never getting her back, so their reunion and the God of Thunder getting the wisdom from his mother he so desperately needed arguably had more meaning than a reunion with Jane.
Still, it was nice to see Natalie Portman’s Jane Foster back in the MCU if only to remind us of how she played a big part in Thor’s early entry into the human realm. It’s also cool that the relationship between Natalie Portman and Marvel has thawed enough that she recorded the voiceover and showed up to the premiere. I wouldn’t expect this means that Jane Foster's Thor is coming in Phase 4, but you never know.