Visible crew/equipment: When Dewey yells for Lois because the bow was put on the present, if you look to the left of Lois, you will see a crewmember kneeling down, handing Lois the red dress, who is holding a bucket of water. He quickly gets out of the camera's view. [This is on the DVD of the first season. Someone said on the audio commentary that after catching it, they deliberately left it in to see if anyone would spot it. It's still a mistake, but that's why it's there.]

Revealing: In season 5, second episode, in an imagination sequence Reese and Malcolm are throwing around Jamie, but you can see it is a doll.

Continuity: In the episode "Bride of Ida", in the scene where the grandma is talking at the table with Reese and Malcolm, notice the bottle on the table next the the grandma, between takes the cork from the bottle goes from being on top of the bottle to next to the bottle, it changes in almost every different shot.

Visible crew/equipment: While Malcolm, Reese, Dewey, and Francis are deliberately making their house messy, you can see right above their ceiling a bright light shining down and a black background. It shows that they film their interior of their house on a set.

Continuity: Episode 111 Season 6 "Pearl Harbor" Lois and Jessica enter the house after coming back from going to a musical. As Lois comes through the door her purse slips off her shoulder and she catches it around her elbow. In the next shot a second later, the purse is back up on her shoulder.

Continuity: Season 5, Episode 13, "Lois' Sister." When Susan arrives Hal is holding Jaime, and the baby's entire body changes position between shots repeatedly - in some shots the front of Jaime's body faces Hal, yet in others Jaime's back faces Hal.

Continuity: When Malcolm is trying to get the TV back to the channel he was watching, he picks up a big remote and finds the channel which the video camera feed is on, but the remote he is holding on the TV is a smaller one. It then cuts back to Malcolm who is moving his hand away from the remote he just put down and it's the bigger one again.

Continuity: Season 6, episode 7: "Hal Sleepwalks"; At school, Dewey stops the shouting match between the two opponents. In the shots facing Dewey, the boy's arms are held way up high in front of him, but in the shots facing the kids, the boy's arms are down at his sides.