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.
Character mistake: Invasion of the Yokel Snatchers: When Homer and Bart witness Cletus getting abducted, Bart tells Homer "they're torturing that yokel", almost as if Bart doesn't know who he is. The Simpson family has interacted enough times with him throughout the series to know who he is and that his name is Cletus.
Continuity mistake: Mob Rules: When the mob begin cheering after Quimby bans Grand Theft Scratchy, they are standing on the curb. When the shot cuts, the mob is now standing on the road and Marge and Lisa are the only ones standing on the curb.
Continuity mistake: Mob Rules: When the Scratchy statue is knocked down, the head rolls away and crashes into Town Hall causing part of the building to collapse. Two window frames can be seen falling beneath the rubble. When the shot cuts, the window frames are suddenly above the rubble.
Revealing mistake: Mob Rules: After part of Town Hall collapses, the shot cuts to Marge and Lisa. Lisa can be seen holding a lit torch, but for the first frame of the shot, the fire doesn't appear to have been animated onto the torch. The fire just pops up on-screen a few frames after the shot starts.
Continuity mistake: Bargain Bin: When the mothership flies away from the Simpson house, the family are shown standing next to a small wall. In the next shot, they are standing a few meters ahead of it.
Continuity mistake: Bargain Bin: When the family are in the living room looking at the Video Game FAQs, a drawer can be seen on both sides of the couch. Both of these drawers have a shelf below it, with three books shown each of the small shelves. A couple seconds later, when the Simpsons get transported to the Game Engine, the books have disappeared from the shelf closest to the window.
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: Big Super Happy Fun Fun Game: When Milhouse loses his powers and hands Homer and Lisa the keycard, the amount of rocks on the ground change between shots. At first, there are two rocks behind him to his left, but when the shot cuts, there is only one rock behind him to his right.
Continuity mistake: Big Super Happy Fun Fun Game: When Milhouse finishes shrinking back down to human form, the keycard suddenly appears in his hands when the shot cuts.
Continuity mistake: Big Super Happy Fun Fun Game: The giant toilet in the village has an additional section added onto the right-hand side of it, which has three coin slots and is used to insert the Sparklemon into. When Mr Sparkle goes to clean up the village, this additional section has disappeared from the toilet.
Continuity mistake: Big Super Happy Fun Game: In the opening shot of the end cutscene, the coin slots on the giant toilet are shown with the middle slot ahead of the other two. When Homer and Lisa go to insert the Sparklemon into the slots, the three slots are more in line with each other and stay that way for the rest of the scene.
Continuity mistake: Big Super Happy Fun Game: When Homer and Lisa first approach the giant toilet and Mr Sparkle appears, Lisa is standing so that her hair is positioned behind Homer's left arm. When the shot cuts, her hair is positioned in front of Homer's arm.
Continuity mistake: Invasion of the Yokel Snatchers: When the alien starts taking a whiz in the fountain, cracks can be seen on the mall behind it. The cracks appear to start from the ground, going up the building by a few feet. In the next shot, those cracks have disappeared.
Continuity mistake: Invasion of the Yokel Snatchers: When the security guard confronts the alien taking a whiz in the fountain, that one alien appears to be the only alien in sight. When the shot cuts back to Homer and Bart, two extra aliens have suddenly appeared.
Continuity mistake: Invasion of the Yokel Snatchers: When the water fountain is first shown, there are two rows of sprinklers shown around the fountain spraying water. One row of sprinklers around the edge of the fountain and a second row along the interior. When the shot cuts, the row of sprinklers around the edge of the fountain are no longer spraying water, leaving only the interior row spraying water.
