Corrected entry: The Sovereign Priestess states that the Guardians were hired to kill the monster at the beginning of the film because they "could not risk the lives of their own", but later, it's shown that they pilot all of their ships remotely, thereby not risking any of their own lives.
Corrected entry: Ego's entire plain revolves around finding an offspring powerful enough to help him. After searching for hundreds of years and children, he finally finds Star-Lord, and just when he's about to succeed, he screws it up by telling Peter that he killed Peter's mom.
Correction: He only needs Star-Lord's inherited power for his plan to succeed. Star-Lord doesn't have to be a willing participant. Ego even mentions to Star-Lord when he impales him that he can spend a long time functioning as a battery of sorts. One way or another Star-Lord would have turned on Ego, as either Gamora or Yondu would have informed him of all of Ego's dead children.
Corrected entry: Peter Quill uses an old Mattel electronic football game that he has modified to be some sort of tracking/radar device. Where did he get it? When he was abducted, all he has was his Walkman and mix tapes. Not only that, but with access to advanced technology, why would he even need such a device?
Correction: You know, just because Starlord does some crazy stuff to a device to make it do something else than it was originally intended for without it actually making sense does not make it a plot hole. He just made the decision to do that, and it was possible to do it. Its not a mistake at all. He also could have gotten the device from anywhere, he's been around. Some other aliens could have stolen things from Earth and he bought it from them (or stole it).
Or he had it in his backpack at the time when he was abducted, since he did have a backpack.
Corrected entry: When Baby Groot finds and brings items thinking they are what Yondu wants, he brings a desk that screeches when he drags it. There is no way he could have dragged it any great distance without alerting anyone, including the guards (seen later) posted nearby. Or if he were closer, Yondu or Rocket would have stopped him. Or even put it back (it's not seen again).
Correction: That's part of the joke.
Corrected entry: At the very beginning of the film it says that it's 1980 Missouri with a nuclear power plant in the background. The plant in the film has 4 cooling towers, but the only nuclear plant in Missouri (Callaway Nuclear Generating Station) has only one cooling tower and it didn't begin operation until 1984.
Correction: Coal power plants also have cooling towers. The actual power plant in the background of the film is Plant Bowen in Georgia, but plenty of coal power plants across the US feature cooling towers.
Corrected entry: The wound and blood on the left side of Starlord's face disappears at the end of the film.
Correction: By the end of the film the wound on Star Lord's face disappears because he wills it to disappear using his Celestial power. It's subtle but you can actually see it disappearing.
Corrected entry: Before he dies, Taserface sends the Sovereign the coordinates for Yondu's ship before the bulk of it explodes. But, they then do over 700 jumps to get to Ego's planet. How could the Sovereign possibly track them there?
Correction: They had the coordinates for the ship, so presumably they could lock on and track it or be able to find it with deep-space scans.
Correction: The plan to kill the Abilisk did not involve using ships. It involved people on the ground fighting it. This would have put their people at risk.