When Max is going through the crowd, the people don't get out of the way, they disappear.
At the end of the movie, when Goofy is blown into the air by his exploding car, his boots remain on the ground. However, they're back on his feet when he crashes through the roof.
When the student body is chanting Max's name, Bobby is shown hanging onto a statue. Just a moment later, when Max high-fives the students on the school bus, Bobby is now shown on the bus.
When Goofy and Max enter the motel room, the waterbeds are see though and have fish in them. Later, when Goofy comes back, the beds are no longer see through.
Max and Goofy's shoes disappear and reappear throughout the "Nobody Else But You" sequence.
When Goofy puts the 8-track cassette of "High Hopes" in the radio, he pushes the button on his side of the radio to start "High Hopes" playing. However, in real life, an 8-track tape starts playing directly after it is put in, so Goofy wouldn't have had to push the button to start the tape.
During the "Open Road" song, the dotted lines on the road change to yellow instead of staying white. When Goofy almost gets hit head-on by a truck, the white center line should be yellow in the two-way traffic.
Goofy and Max fight over whether to listen to "High Hopes" on the former's 8-Track cassette or rock 'n' roll music on the radio by pressing the two buttons on their respective sides. In real life, the two buttons on the 8-track stereo the father and son press are the "Program" button that skips ahead to the next of four different programs on the cassette, and the "Track" button which advances to the next track within the same program. Max would actually need to eject the cassette out of the player just to listen to his preferred music on the radio while Goofy would need to re-insert the cassette so he can go back to listening to it, and vice-versa.
On the Grand Canyon, Max kicks the tire of his father's car and then leans on the car from the rear, sending it rolling out of control. It would be impossible to do unless taken out of park with the key in the ON position regardless if the engine is running or not.
After observing Goofy's map, when Max erases the line and redraws one towards LA at the junction line using a pencil that was with it in the glove compartment, he is able to erase and redraw the line on the map without any trouble. In reality, you can't draw on single layered paper without anything firm enough under it easily without the pencil tearing right through it. Plus, on the contrary to this reality, as Max is attempting to redraw the line, the pencil head breaks, which can only happen on a hard surface.
During "After today" when we see Roxanne walking past Max her reflection can be seen in the window. But her reflection has a mole, and it's the right side of her face that would be reflected in the window. And she only has a mole on the left side of her face.
During the song "Nobody Else But You," the changing perspective of the cave ceiling is wrong when they first enter.
When Goofy looks in his rear-view mirror after the radio breaks, the reflection shows the opposite side of the car.
The structure of Goofy's map changes throughout most if not all scenes that it's shown.
While Max is getting ready to do his show in the school auditorium, PJ's mouth doesn't move while he's talking.
In the scene where the students are yelling "MAX! MAX! MAX!" the camera pans and the jocks mouth is not in sync with "MAX"
Somehow, after the Powerline Concert; Goofy and Max get their car back even though it was lost during the waterfall incident.
Somehow, Goofy knew where Roxanne lived without Max ever telling him.
When Max has Goofy turn to go to Roxanne's house, he's wearing the fishing suit. When he gets out he's not wearing it any more.
Lester introduces his possum band from left to right as Buford, Beulah, and Mordecai. When Mordecai asks Lester if ready to yodel, he replies, "Sure am, Buford!"
In Latin Spanish dubbing, Opossum is referred as Raccoon by Goofy and Rat by Max Goof.
Max writes with his right hand when he writes letters to Roxanne while on vacation with Goofy. However, he uses his left hand to hold a fork while he and his father eat breakfast while on the road trip, and he catches the ball with his right hand like a left-handed person while at a baseball game.