I’d run across mention that Howard the Duck makes an appearance in the “Avengers Assemble” scene in Endgame. Tonight, I finally tracked it down to see for myself.
He’s visible for just a second, right after The Wasp makes her appearance and immediately before the camera cuts to Thor. You can see it here: https://www.youtube.com/watch?v=G1bSmAsswg0&t=92s
And then, since I was already headed down the rabbit hole, I went and watched the movie. Lea Thompson was as cute as I remember, but … yeah, this wasn’t one of Marvel’s best movies.