Development Hell: The fifth movie has gone through a prolonged development cycle which has repeatedly stalled. Originally intended for a 2013 release date after Shrek the Third, the latter movie's poor critical reception caused plans for the fifth movie to get cancelled, with Shrek Forever After becoming the series' Grand Finale as a result. The movie's production since restarted in 2016, but has since been repeatedly delayed with next to no information nor a concrete release date in sight, with rumors waffling on whether it's actually a sequel to Forever After or an outright Continuity Reboot.
Fake Brit: Canadian actor Mike Myers voices Shrek, who has a thick Scottish accent, in all the mainline movies.
Jason T. Lewis voices Donkey in the Shrek-related DreamworksTV videos, with Mick Wingert (best known as the substitute voice for Po of Kung Fu Panda fame) voicing Shrek in a handful of them, as well as the videos' endtag (even in videos where Gough voices Shrek).
The game was supposed to show off the hardware capabilities of the Xbox, and was actually supposed to be an original IP before being repurposed into a Shrek game.
A PlayStation 2 port was planned but was cancelled due to TDK Mediactive being acquired by Take-Two Interactive which led to the company losing the Shrek license.
Other games
What Could Have Been: The Pocket Shrek app was meant to have Fiona as an interactable character alongside Shrek, Donkey and Puss and even got advertised in-game, but she was cancelled when the app went offline and stopped receiving support.