At the begin Ego is running down through the woods with Meredith, in a split second long shot she is wearing Ugg Boots however, in the later shots of her feet she is wearing a pair of heels.
Yondu tells Rocket he found them by adding a tracer device to Peters ship. However, Peters ship was built by the Nova Corp at the end of the first film after being destroyed.
Disagree:The ship could have been unattended. There is no record of time between Yondu leaving and Quill being shown the ship. Plus they say, "we salvaged as much of the ship as possible". The tracker may have always been there.
When Peter Quill is talking to Gamora on Ego, Gamora tosses a radio on the chair. A moment later it is gone, but then appears at the end of the scene when she picks it back up.
Stan Lee's cameo character, an informant for the Watchers explains that in his experiences on Earth, he was a Federal Express employee. This is a direct reference to a past MCU film, Captain America: Civil War which was released in 2016. The MCU timeline also places the events of the film as 2016 as well. However, Guardians of the Galaxy Vol. 2 takes place in 2014, just two months after the first film. So the Watcher Informant would have no way of telling them of a job he had on Earth if it never happened in the chronological timeline.
However, this error can be argued by saying that he could be referencing to a past event, and not his direct cameo in Civil War. This can only be solved by relying on the possibility that if the Stan Lee cameos in all MCU films are the same person, it would have to be that the Informant would have to continuously switch jobs (he is seen as, for example, a Smithsonian Security Guard in Captain America: The Winter Soldier and a Bartender in Ant-Man) throughout the MCU timeline.
In one of the final scenes, Yondu is shown being cremated while he still has the prototype yaka-controller (mohawk) on his head. In one of the credit-scenes, Kraglin is seen using the same prototype, which would have been destroyed in the "fire".
When Peter's ship is crashing into the forest Drax is still outside being pulled along on a rope tether. As soon as the ship hits the first tree the ship would have slowed down but Drax would not have. He should have piled into cargo hold but instead he stays outside hitting trees.
The lengthy action finale occurs at the center of Ego's planet, which is repeatedly depicted as having a gravitational "down". This is an impossibility as the mass of the planet would be evenly distributed around the characters, making gravitational pull equal in all directions, and causing the center to be a zone of weightless microgravity.
When Ego is showing Quill how to create the ball of energy, he places Quill's hands with palms facing each other. The camera angle changes and Quill's hands are facing up.
When Rocket escapes with Yondu, he asks if they still have any of Peter's old music on the ship. The song they put on the intercom is "Come a Little Bit Closer" by Jay and the Americans, which is on Awesome Mix Vol 2. Peter didn't get that tape until the end of the first movie, long after he was staying on Yondu's ship.
Peter Quill has a shiny metallic plate-like object behind his right ear, including when he is in casual attire. However, when he is dancing with Gamora on Ego's Planet, he is markedly without it. In all other scenes on the planet, before and after, he is wearing it.
Peter calls Rocket a Trash Panda. The expression was first coined on the internet in 2014, the year in which the film takes place. However, the Guardians have not had any contact with Earth to this point, so Peter would not be familiar with the term.
Unlike the iconic Walkman and headphones, the headphones used with the Zune are not original Zune headphones.