The following contains spoilers for Black Panther. Bookmark this page and come back after you've seen the movie and stayed through the credits.
Black Panther is a Marvel movie, and that means that the story isn't over when the credits roll. The newest entry in the Marvel Cinematic Universe has a pair of scenes that take place after the movie "ends." One is designed to be an exclamation point on the end of the movie itself, while the other sets up what is likely to be an important aspect of Avengers: Infinity War. This is your last warning. From here, we're in spoiler territory.
Since most Marvel movies don't open with credits, many of the films start their credits with what would otherwise be the opening credits, a colorful display that focuses on the major players in the movie. This portion ends with the title and from there we move into the first scene. T'Challa (Chadwick Boseman) has arrived at the United Nations and he addresses the general assembly with a message that Wakanda will no longer isolate themselves from the rest of the world. Going forward, Wakanda will share what it has with the globe. T'Challa provides a message of unity and promises that Wakanda will be part of the global community. This is followed by one of the UN Representatives vocalizing what many others are probably thinking: what exactly does a nation of African farmers have to offer the rest of the world? The scene ends as T'Challa starts to grin, which I believe translates from Wakandan to, "Hey asshole, watch this." We never see his actual response. We don't really need to.
While the scene is clearly here to make the audience laugh and send them home with a smile, that doesn't mean that the scene isn't important in the broader MCU. Based on how Black Panther opens, we know that the movie takes place more or less immediately following the events of Captain America: Civil War. What we don't really know is how long after this Avengers: Infinity War will pick up. Regardless, this moment will likely have huge implications on the next film and the broader MCU. If Infinity War picks up shortly after Black Panther, then the world will likely still be in shock from the revelation that an isolated country in Africa is the most technologically advanced place on Earth. Not everybody will be happy with this news and the globe will certainly be dealing with some degree of upheaval. If Thanos arrives on Earth during this period he may be able to use the chaos to his advantage. If he's paying attention, he may even decide to use this moment intentionally because he knows Earth will be distracted and won't be ready for him.
Alternatively, if Avengers: Infinity War picks up after some significant time has passed, then the Earth of the MCU will quite simply be a very different place. Wakandan technology will have disseminated to other parts of the planet. The general level of technological access for the planet will have changed. With the Wakandan Outreach centers that are mentioned at the end of the movie, even the inner cities will be vastly different places. If Thanos arrives on this Earth, he may find that he has more to contend with than simply Earth's Mightiest Heroes.
Regardless, as we move forward into Phase 4 of the Marvel Cinematic Universe, the planet will become a different place following this moment. But this isn't the only scene that we get. Read on to find out what else arrives at the end of Black Panther.
From there, we move to the very end of the credits and the scene that will have a more direct impact on Avengers: Infinity War. We cut to three African children who are looking at something, or someone, very closely. We see the kids from the perspective of the thing they're looking at. They then all run out of a hut giggling, and we see Shuri (Letitia Wright) standing outside. A moment later, we see what the children were looking at, as Bucky Barnes (Sebastian Stan), the Winter Soldier, stumbles out, having just woken up. His arm is gone, but he looks otherwise just fine. Shuri addresses him as Barnes, but he asks her to call him Bucky, the two have obviously spoken before and they've been doing something together, as she tells him he has a lot "more" to learn.
While the fact that we'd see The Winter Soldier again was revealed in the first trailer for Avengers: Infinity War, this scene shows us that his deprogramming has already been successful, or mostly so. This means that when we meet him in the next movie, he'll likely already be ready to fight the incoming threat. The fact that he's missing his arm is likely also telling. We'd been given an indication that Bucky would receive a limb upgrade from Wakanda, and the fact that he's working with Shuri, the exact person who would likely construct such a thing, would seem to confirm that. Maybe that's what Bucky needs to learn, how to use his new arm.
The two post-credits scenes in Black Panther are not of the massively shocking variety, but they aren't without their importance. They're the final moments of the Marvel Cinematic Universe before the Infinity War begins.