DEN of GEEK: Ant-Man Review
“Most of Pym’s history is explained in two relatively brief scenes (one of which shows a younger version of Douglas in perhaps the best onscreen de-aging we’ve ever seen), while an extended sequence halfway through the film features a surprise cameo that you’ve probably heard about by now”.
http://www.denofgeek.us/movies/ant-man/247485/ant-man-review