In Don't Hug Me I'm Scared 6, when the machine starts flashing teachers,there are some teachers seen for a split second.
-The plug at the end of the video
-A horse (or a pony)
-A meat cube
The Red Guy and Tony the Clock are also seen during the montage.
The glitched Duck Guy from DHMIS 4 appears too.The clapperboard was first seen at the end of DHMIS 4.