The "Now That's A Knife!" achievement is a reference to the 1980s movie Crocodile Dundee.

"The Night Is Dark And Full Of Terrors" achievement is a reference to the TV show Game Of Thrones.

The "I Live. I Die. I Live Again." and "Oh What A Day! What A Lovely Day!" achievements are references to the movie Mad Max: Fury Road.
Both of the phrases are spoken by the Warboy.

The "I Have A Very Particular Set Of Skills" and "Skills That Make Me A Nightmare" are references to Liam Neeson's phone-speech from the movie Taken.

The "Job's Done" achievement is a reference to the Warcraft franchise.