First off, where the heck did Loki come from? I really enjoyed the opening title music. I like the scene where they recruit Captain America to the Avengers. I liked how they cut from hero to hero in the recruiting process in the beginning, giving us a glimpse at what each hero was up to during their "break". I like how cap stays old fashioned. Captain America and Iron Man coming together and meeting for the first time was classic and really foreshadowed at Civil War. The writers did a good job showing how they have to have altercations before they come together and they finally come together after a well needed push (Phil Coulson's death). One of the best scenes in the history of movies is the revolving scene around the Avengers as they come together before war. Also I really enjoyed when it cut seamlessly from Avenger to Avenger each fighting their individual battles in the war. Great ending to the end of MCU phase 1. I love Marvel because it combines the world we all know with that of a fictional universe to aid our imaginations in creating fantasies about a combination of these universes where anything is possible.
In the mid-credits scene the Other speaks to his master (undoubtedly Thanos) about the failed attack on earth.
In the end credit scene the Avenger are eating shawarma.
Stan Lee makes his appearance in a short news interviews saying "Superheroes in New York? Give me a break"
Stone Tracker: The Tesseract is used by Loki in this film and now is in the hands of the Asgardians, it is known as The Space Stone.