Continuity mistake: At the end of the last movie, Tails did not have the yellow small bag that he has in this one.
Other mistake: When Robotnik, Stone, and Knuckles are eavesdropping on Sonic and Donut Lord's text conversation, the third text is supposed to be from Sonic but it appears as Donut Lord's text, on the wrong side of the conversation. (00:40:00)
Revealing mistake: When Sonic and Tails arrive in Green Hills on the biplane, Tom and Maddie are looking up at them, but not focused on the same point. Instead, Maddie is looking to the left, and Tom to the right.
Continuity mistake: When Tom and Maddie go to check on Tails when he tries to get up on the beach to help Sonic, the scenes are cut badly and show Maddie leaning down two times.
Continuity mistake: When Knuckles and Sonic are on the beach, they are sitting side by side by the pile of sand, but when Sonic sees Tails and turns back to look at Knuckles, Knuckles is sitting much further away.
Continuity mistake: Towards the end of the movie, after the baseball game they go to the blue Chevy truck. One scene shows the blue truck with wheels from a Toyota Tacoma, then seconds later shows a different set of wheels on it.
Revealing mistake: During the dance-off scene, when Sonic steps on top of the unconscious guy's stomach, his right foot does not cast any shadows.
Revealing mistake: During the final fight scene while Tom is racing around in the yellow truck, you can see the gear selector is in the highest position the whole time which would indicate the vehicle is in park instead of drive.
Continuity mistake: After Sonic takes off to try to get to the Master Emerald before Robotnik and Knuckles, Tails attempts to fly off. He has his backpack on his back. But a few shots later, from behind, his backpack is no longer on his back.
Continuity mistake: During the baseball game between Sonic and the others, the sun on the floor changes between shots.
Continuity mistake: When Tom meets his friends in Hawaii and all unite holding cocktails, his wife's arm is raised or lowered depending on the shot.
Visible crew/equipment: When Sonic creates the magic hole for the couple to travel to Hawaii, on his lenses and the dog's four stage lights are reflected, neither the living room nor the bright hole are nowhere to be seen.