Michael leaves to buy a universal remote just after he develops a cold, then skips his having it, but at the end of the film when he returns to Bed, Bath, & Beyond, he doesn't cough as he did when he was leaving.
When Michael flashes back to the time he and his wife first kissed, Michael and everyone else seem to be wearing 80's attire. When Michael and Donna kiss the song "Linger" comes on, but that song didn't come out until 1993.
During the camping flashback scene, the O'Doyle boy tells everyone to come to the motor home to watch "Three's Company." The flashback scene was supposed to occur in 1976. The first episode of "Three's Company" didn't air until March of 1977.
When Michael pulls up to the traffic jam (next to the singing guy), he yells "Will you stop talking and fix the sewer!" However his mouth is saying something else judging by his reflection in the driver's side mirror.
When Michael first goes back to his old house after getting fat, the radio says it 2017 but when we see him again in the hospital, Donna says it's been six years since the accident. Out in the lobby when he sees his son, the intercom says it's 2018 though it should be 2023. Shortly after when he finds out his father died and he goes to the cemetery, his father's grave says he died in 2021.
During breakfast with Janine and Michael when Janine is shouting at him, she has a rabbit teddy in her hand when shouting about her abandoned rabbit. The camera shot then goes to Michael, and when it switches back to Janine the rabbit teddy has vanished.
When Michael comes home and parks in the driveway his car is very dusty, in the scene that follows where his son and his friend is throwing the baseball, the car in the background changes in between shots from dusty to clean.
The position of SunDance changes repeatedly throughout the beginning scenes. When we first see him he is curled up at the end of the sofa, in the next shot he is curled up with his head stretched out, next shot he is lying outstretched with Michael's feet on him, and the next shot he has gone completely.
When Michael asks to watch the last time he saw his Dad, at the first run (without pauses), when his Dad is leaving, Ben is at the right side of the desk. After Michael rewinds and pauses a few times when his Dad is leaving, Ben is at the left side of the desk.
When the kids and Donna come downstairs to find that Michael has bought the kids new bikes, the green box for Donna is seen behind Michael on a small table without a bow. In the next shot, when Michael is giving the box to Donna, it has a bow.
When Michael is first discovering the remote's power, he uses it to silence the dog. The scene shows a dog barking, but there is no sound. He then uses it to restore the dog's barking, and the camera cuts to the dog, and we hear barking. The camera cuts back to Michael. When it briefly cuts back to the dog once more, the dog is again silent, although Michael has not used the remote.
When Michael is playing with the toy, just before he picks up the remote for the helicopter, a cameraman can be seen in the reflection of the window behind him, just below the reflection of the yellow duck and behind the reflection of the chair.
The interior layout of the house does not match the outside - The outside shows a 1 story house that is flat along the front, and that garage on the right side. But inside there is a staircase, and the front entry sticks out further than the rest (so it could not be a flat front house) and in the beginning when Michael is leaving to look for a universal remote, he goes to the garage, but goes on the other end of the house than what is shown outside.
When Michael tells his daughter he's going to teach her calculus she corrects him implying that he doesn't know how. However, being an architect he would have had to take a calculus class in college at some point.
Ben and Samantha are two years apart. The end credits depict three actors for both Ben and Samantha at different ages. At the start of the movie, Ben is 7 and Samantha is 5. Then, after the one-year jump, Ben is 8 and Samantha is 6. Then ten more years pass, Ben is 18 (the credits say he's 17) and Samantha is 16 (the credits say she's 14). Then a six-year jump, Ben is 24 and Samantha is 22 (the credits say she's 27). Going by the credits, Samantha is suddenly older than Ben.
Technically, the remote should not have fast-forwarded when Michael was mentioned a second promotion since the remote only becomes automatic when the same situation repeats itself various times, but since he only fast forward once in the case of the partner promotion, the remote wouldn't have done it automatically, and he only did it up to the point when he actually received the promotion, not past his getting one.
Michael shouldn't have survived his heart attack and the subsequent recovery, because it should have been considered an illness - which the remote was "programmed" to skip. He should have immediately died before he had it, instead of soon after removing himself from life support.
The goof items below may give away important plot points.
At the end, Michael picks up the note beside the universal remote. In a back shot we can see through the paper, and we can see the amount and positioning of the writing. In the next shot showing us what is written on the letter, the amount and positioning of what is written on the letter has now changed.
At the end of the movie when Michael goes to call his dad he puts his hat on the counter and there is a fruit bowl on the table. He picks up the phone and sees the remote on the table with the note. With the camera changes his hat moves once but the fruit bowl is in a different position with every shot. Also, in the last shot a butter dish and an open box of Chinese take-out appear on the table.
During the scene where Michael is walking out of the hospital after his heart attack at Ben's wedding, you can see circular patterns on the road surface where the film makers rain machines are being used.