YOU'LL BELIEVE A PIG CAN FLY
The one thing I'll say about the pigs is that they're persistent. Actually, I'll also say they're gluttonous, ugly and just plain pong, but that's not important right now. What is important is that they've finally learnt how to fly, using balloons at least. You can't really blame Red. He was expecting another grunting ground assault. He never considered the pigs would float the eggs away using helium-filled hog balloons. Well, maybe you should blame him, just a bit.
Usually at the end of an episode, the King Pig is brutally beaten and looks at the birds and the player and oinks while blinking with its left eye. However, at the end of Danger Above, the King Pig does it with his right eye, due to the fact that the birds have hung him upside-down, although technically it's his left eye that blinks, it's really his right eye.
As of the 3.0.0 update, the forest background has a slight difference to the old one, including how the trees are formed.
This is the only chapter that has the pigs shown above, rather than the right during the opening cut-scenes.
This is the only chapter in which the Yellow Bird has a "!?" symbol on its head, rather than a "#" symbol when he looks at the pigs above in the cut-scenes.
This is also one of the two chapters featuring the balloons. The other is The Big Setup.