Avengers: Age of Ultron does not have a post-credits scene, but it does have a mid-credits scene. If you want to read about it, continue on. If not, avoid this post entirely.
First of all, I can confirm that Avengers: Age of Ultron DOES NOT have any post-credits scene of any kind. I stayed by myself at the end of the session and all it showed was text saying “The Avengers Will Return”. We already know this since Avengers: Infinity War Parts 1 and 2 have already been announced. The video showing Spider-Man at the end is 100 percent fake. There were no Spider-man easter eggs (to my knowledge) in the entire movie.
However, Avengers: Age of Ultron does have a mid-credits scene that sets up the events for Avengers: Infinity War Parts 1 and 2. It’s a short scene, but we see Thanos. Thanos manages to get a hold of the Infinity Gauntlet and puts it in his hand. He says: “Fine, I’ll do it myself”. That was the whole mid-credits scene. It was very short, but very sweet.
It’s worth mentioning at this stage, Thanos only has the Infinity Gauntlet, but not all of the Infinity Stones yet. Avengers: Age of Ultron was more of a conclusion to phase two while phase 3 begins. Phase 3 will show us how Thanos goes out to acquire the rest of the Infinity Stones.
Anyway, Avengers: Age of Ultron was a fun ride. It will not open in North America until May 1st.