This is just a random list of things I found interesting, pictures and rules feel free to add
Page 57, in the picture one of the death guard has a funny looking helmet and another has a grey knight helmet
Terminators don't have the deep strike rule
That the Luna wolves earned their name from the pacification of Luna
The Luna wolves where the first to wear wolf pelts
Page 131 one of the death guard has a chaos style backpack
Page 203 one of the death guard has a different helmet again
The mechanicum land raider has a special rule "blessed autosimulacra" but I can't find the rule anyway in the book
The emperors children was reduced to 200 by the time they found Fulgrim
Dreadclaws are flyers