At the beginning when Mitch is talking with his father about the upcoming wedding, Mitch's hair changes colour, length, and style several times back and forth.

When Mitch is having sex with Mona on the bed, her bra is off and then a few seconds later it is on again.

As Mitch (in Dave's body) goes to Dave's work for the first time, his jacket is buttoned up as he walks in but in the next shot after the man says "Early morning on the golf course, Lockwood?" his jacket is unbuttoned. Then when he goes in the room with all the food immediately after, his jacket is buttoned again.

When Mitch is pushed out the door on the movie set to begin shooting, the door is room #69 and room #32 is across the hall. The next cutaway shot shows him from what would be the hallway, and he is being pushed out of room #32 now.

When Mitch, being Dave, is having an argument in bed with Jane, it looks like she's going to push him out with her arms, but in the next scene, she kicks him with her leg.

Dave had to work four jobs to put himself through college, according to a conversation between his best friend and his wife, but at the celebration for making partner at his firm it is said that he had a full ride to Princeton. But they then go on to say he graduated from Yale Law with no mention of a scholarship. It is most likely that the 4 jobs were to pay for Yale.

Switching bodies seems to happen after falling asleep while switching back is instant. This is incorrect; switching back was not instant. Dave and Mitch just remembered the blackout from the initial switch and left the mall during it to avoid security. They didn't know for sure they would switch back, as evidenced by how they reacted to learning they were themselves again the following day.

In one of the office scenes, when 'Mitch' (Reynolds) is in 'Dave's' (Bateman) body, an open game of Freecell is seen on the computer. Yet there are 4 cards occupying the ace boxes and 4 cards in the 'free cells' while the rest of the cards are in the correct starting position. This would mean that there was an extra 8 cards in the game.

While at the ballgame, immediately before it starts raining, the stands are full. But by the time Mitch (as Dave) can get his umbrella up, the seats behind him and Sabrina are impossibly already vacated.

When Mitch (in Dave's body) says his new role is his "big break" to Dave (in Mitch's Body) outside the district office, his mouth does not match what he says.

When Dave (in Mitch's body) tells Sabrina he's on his way to see Dave just before she gives him the baseball tickets the motion of his jaw doesn't match the audio.

Assuming her house key was in her purse, Sabrina would not have been able to get into her house when she went home after being at Mitch's apartment and accidentally leaving her purse there (which is also a contrivance since most women do not forget their purses); unless she left her door unlocked, which is also hard to believe that a smart single woman would do.

The day after they switch bodies, Dave (in Mitch's body) rips into Mitch (in Dave's body) for failing to pick up the twins from daycare the day before. But in reality, Dave should be blaming himself for not telling Mitch that he needed to pick them up as well as Cara. Either Dave did not know it was his day to pick the twins up or he was so distracted by the body switching thing that he must've forgotten to mention that they needed to be picked up.

The tattoo that Dave (in Mitch's body) got in the middle of the night with Sabrina is not shown until almost the end - after they're each back in their own bodies. The tattoo on Mitch's back is a drawing of Dave, but the tattoo artist would not have known what Dave looked like and it would be odd for Mitch to carry a photo of him in his wallet.

The shadow of the boom mic can be seen as Mitch and Dave are talking in Dave's office before Sabrina walks in.