Continuity mistake: Game Over: In Bargain Bin, when the mothership fires on the Simpson house, it destroys the mailbox. When they return in Game Over, in the establishing shot of the house, the mailbox is suddenly back and intact.
Revealing mistake: Mob Rules: When Marge and Lisa witness Martin carjacking Ned, in the shot of Martin saying "Gimme your ride, jerk", Marge raises her hand to her mouth. When she raises her hand, part of the baby carrier she is carrying Maggie around in is not fully drawn in.
Other mistake: Mob Rules: In the opening cutscene for Bartman Begins, Uter, Ralph, Jimbo, Dolph and Kearney are seen queueing outside the Sequel Stop store. In the opening cutscene for Mob Rules, the exact same group of people can be seen coincidentally queueing outside the same store, despite the passage of time.
Revealing mistake: Bargain Bin: When the Simpsons are sitting at the computer, the Ethernet cable seen coming out of the back of the computer doesn't appear to lead anywhere. The Ethernet cable is shown attached to the computer, but it ends after a few inches and is not attached to anything else. The animation for the cable was incomplete.
Continuity mistake: Big Super Happy Fun Game: When Homer is handed the Sparklemon after he and Lisa defeat Ralph, his left arm is raised when he grabs onto it. In the next shot, his left arm is at his side and the Sparklemon has disappeared. The same mistake is also made when they defeat Sherri and Terri.
Plot hole: Game Over: When the Simpsons return from the Game Engine, Springfield is still in the middle of an alien invasion. Lisa then comes up with a plan to build a stairway to heaven out of Springfield buildings, but she is able to build the stairway without the aliens interfering in any way. In fact, there appears to be no sign of the aliens at all, despite the fact that they are currently in the middle of invading the town.
Plot hole: Five Characters In Search Of An Author: The opening cutscene ends with all five members of the family entering the gates to Matt Groening's mansion and walking down the path. Another cutscene then begins to play that continues on immediately after the previous cutscene where Homer and Bart are outside the mansion, but Marge, Lisa and Maggie are nowhere in sight. Since this cutscene continued on right where the previous one left off, there's no way they could have split up so quickly.
Character mistake: Bargain Bin: When Bart is researching the Simpsons Game online, he says "Bartman, eating contest, alien invasion, slaughtering dolphins, it's describing everything we've done all day." Even if we were to assume the events of Bartman Begins through Mob Rules took place over one day (which is already hard to believe), the family were shown sitting at the breakfast table in the morning during the Mob Rules end cutscene, so there is no way the entire game took place over the course of one day.
Other mistake: Big Super Happy Fun Game: When the three Sparklemon confront Milhouse, they begin beating him up, but it is very clear their fists are not touching his body.
Continuity mistake: Five Characters In Search Of An Author: When Matt Groening stands up after being beaten by Homer and Bart, he starts thanking Marge. When he says this, he is standing at an angle perpendicular to Lisa. In the next shot, he and Lisa are standing directly in front of each other.
Other mistake: Five Characters In Search Of An Author: When Bart begins inserting the key cards into the slots, we can see that all four of the slots are all different colours (purple, blue, red, pink). The key cards are supposed to be inserted into the slot that matches its colour. But he is shown inserting the blue keycard into the red slot.
Continuity mistake: Medal of Homer: When Bart asks Homer if he can get some wine, Homer rejects his offer saying he's an American kid. When he says this, no-one else can be seen standing next to the truck behind them. Abe then suddenly appears in the next shot, saying "God bless America" while standing next to the truck.
Continuity mistake: Medal of Homer: When the Mayor hands Homer the painting, the two are standing right next to each other. A couple seconds later, the Mayor is meters away from Homer.
Continuity mistake: Medal of Homer: When the Mayor of the village shows Homer the painting, he has both hands placed on each side. The hand placed along the left side is near to the middle, whereas the hand placed along the right side is higher up. But in the next shot, both hands are level with each other.
Continuity mistake: Medal of Homer: When Abe tries to shoot at Private Burns on the boat, Burns leaps onto the ground for cover. He lands flat on the ground, but in the next shot, he is suddenly standing.
Revealing mistake: Medal of Homer: After Homer says "It's the Civil War, duh", it cuts to an angle behind Homer and Bart. For the first frame of the shot, a couple of the lights in the village are not switched on and no smoke can be seen coming out of the chimneys. The lights and chimney smoke just pop-up on screen a couple frames into the shot.
Continuity mistake: Grand Theft Scratchy: At the start of the opening cutscene, when Marge is commenting on the neighborhood, the shadows on the ground change between shots.
Continuity mistake: Grand Theft Scratchy: When Marge says "Look at this place. Graffito, bottle and bags", she is standing upright. In the next shot, she is suddenly hunched forward towards Lisa.
Continuity mistake: NeverQuest: When Homer climbs into Patty and Selma's ash tray, cigarette ash around the keycard suddenly appears when it cuts to the close-up shot.
Other mistake: Bargain Bin: When Marge and Lisa get out of the elevator after arriving at the theatre, Maggie cannot be seen in Marge's arms. She was transported to Game Engine along with the other Simpsons and was being carried by Marge. So there is no reason at all why Maggie would be absent here.
