I had noticed that despite varying degrees of success, the two TV series, the movies and Legacy all have aspects that would later be used in the main games. I think these could go into the main articles to add some intrigue.
Conquest had the first appearance of the Deadly Alliance and a concept for a character in the games. Noob Saibot's liquid composition would later be used in MK9. I believe the Konquest mode was likely named after the series, possibly as a sign of respect considering their premise.
Defenders of the Realm of course had Quan Chi.
The first movie retconned Kano to be half Australian in tribute to Trevor Goddard. Shang Tsung's catchphrase of course snuck its way into just about every game he's ever been in since.
Annihilation unfortunately had to be the one to explain what MK3/UMK3/MKT didn't explain: why the Elder Gods didn't step in and stop Shao Kahn despite explicitly breaking the rules, something that made its way into MK9.
I don't think anything has yet to be lifted from Legacy though Skarlet's cyber form does look a lot like Sektor's.