A comparison between a frame from the 2D/3D set captured by KK650 and the "same" frame that I've captured from the UK 2D standalone release...

Being a daylight scene the colour difference probably isn't as marked as it is in some scenes. If you look very closely though you'll see that this isn't actually the "same" frame. It more obvious when I overlay the two...

Everything in the foreground and background is at a different angle. I'm 99.9999% sure this is because the standalone 2D is just a scan of the left or right eye from the 3D Blu-Ray. It's not the first time I've noticed this problem...
Dredd 2012 French Blu-Ray Review
I'm not sure if this is because preparing a seperate 2D home-video master is expensive, or if sometimes studios just don't really care and assume nobody will notice. Maybe this is standard practice wth Marvel. I wasn't that impressed with the 'Winter Soldier' BR either but unlike Guardians, I hadn't seen that movie 3 or 4 times to be able to instantly notice when something was off.
Another couple of shots...

^ This one is terrible, like a photocopy, of a painting, of a film... in the dark.

...and what is up with the blue splodges of flat cyan in the background of this ^.
This and the UK Dredd 2D Blu-Ray really shakes my faith in the format. I'm going to treat any release of a 3D film with deep suspicion from now on.