Continuity mistake: At the end of the movie, when Star Lord is dancing to distract Ronan, Ronan is holding the hammer so the head is to his left, but when Drax shoots the hammer the head is now on his right. It changes instantly between shots. (01:41:45)
Continuity mistake: When the Dark Aster enters the atmosphere at the end of the film, its wings untwist as it descends, in most of the scenes afterwards and the hologram the ship's wings are still twisted, then later during the battle they untwist again.
Continuity mistake: When Quill and Gamora first meet and get into a fight, Gamora grabs the Orb Quill is carrying and runs. Quill throws a sort of laser-based "lasso device" that snares her legs and causes her to fall. She pulls it off, and immediately in the next shot, it's vanished from the ground between cuts. It also had mechanical components, so even if the laser vanished, the mechanical pieces should still be on the ground.
Continuity mistake: The space between Drax and Ronan changes between shots when Drax tries to stab him.
Other mistake: At the end when the ship crashes that part of the city is leveled - we see injured people, but no one is covered in dust or dirt thrown up by the impact - everyone is clean.
Continuity mistake: After Ronan pushes Rocket away near the end of the film, Peter is seen with his hand near his face. However, in the very next shot, his hands are by his sides.
Continuity mistake: During the prison break, Gamora kicks a guard with a black baton that she needs to take. When she first kicks him, her hands are up, and the next shot she's grabbing his wrist and the baton is in front of her body. In the next shot, it's behind her head and the next shot the baton has moved to a 3rd position, across her leg.
Chosen answer: Each realm is actually more of a dimension than a single world. So Xandar would be part of Midgard. The orb is the housing for one of the Infinity Gems. The Tesseract is also an Infinity Gem. The stone in Loki's scepter and the Aether from Thor: The Dark world are two others. All 6 gems can be combined on the Infinity Gauntlet which enables the user to do whatever he wishes just by thinking about it. Wielded by Thanos, among others, in the comics.
Grumpy Scot