Continuity mistake: When Sinestro is talking to the Guardians for the first time in the movie, the last shot of him shows his scar on the wrong side of his face.
Continuity mistake: When Hal is with his nephew, several mistakes occur between shots. When he puts his arms around his nephew, in the first shot he puts his right hand on the boy's shoulder, but in the next it's his left hand that's on the shoulder, then he puts his right hand a second time on his nephew's shoulder. When he's leaning back on both his arms in one shot, in the next he's leaning on only his left arm and then puts his other arm behind him. And the shot where he gives his nephew the present, he suddenly has his right arm resting on his thighs.