sideshow

As nouns the difference between afterthought and sideshow

is that afterthought is a reflection after an act; a later or subsequent thought, action, or expedient while sideshow is a minor attraction at a larger event such as a circus, fair, music festival or similar.

As a verb afterthought

is to expound as an afterthought.

As nouns the difference between sideshow and slideshow

is that sideshow is a minor attraction at a larger event such as a circus, fair, music festival or similar while slideshow is a presentation of a series of photographic slides, usually with a spoken or recorded explanation.