In one of the flashbacks to 1985, as Mary and Ted stroll down the street, she rants about San Francisco 49'ers' quarterback Joe Montana being obscure and underrated, but insists he will surprise by taking his team to a SuperBowl. By 1985, Montana had already won two Superbowls with the 49'ers.
When Ted first arrives at Mary's house for prom, Warren is seen in the background with the Rubik's cube. He has just finished solving it, and holds it up slightly. In the next shot of Warren, he is again finishing solving the Cube and again holds it up.
When Norm and Healy are talking at the bar in the strip club you see a stripper place an ashtray between Norm and Healy. The camera turns toward the bartender than when the camera is back on Norm and Healy now a Tabasco sauce bottle in right in front of the ashtray (previously not there).
When Ted and Mary take Warren fishing, Ted gets a fishing lure accidentally hooked through his mouth, with hooks piercing his lip and cheek. However, in the very next scene (and for the rest of the film) he has no bandage, no wounds and no scars.
Ted and Mary are on their first evening out in Miami. Ted is taking a sip from his 3/4 full glass of rose' when Mary's comment makes him cough. As he puts the glass back down it is now completely empty.
When Ted is helping the old man in the wheelchair carry furniture into his house, the old man drives away in the wheelchair. While driving away, he gets caught on a little tricycle and pulls it along with him. When it shows Ted from the front view going up the steps, the tricycle is sitting where it started.
In the scene immediately following Ted's "interview' with the detectives, we see Pat spying on Mary as she returns to her office. In two back-to-back shots the shadow of the camera operator is cast (and moving) over the black convertible - lower right corner of the shot.
When Healy is trying to revive the dog, he pulls two wires out of the table lamp and taps them together to make sure there is power. Letting hot and neutral wires touch as Healy did would cause a short-circuit and blow the fuse or trip the main breaker, potentially shutting everything in the living room off, and preventing Healy from zapping the dog.
At the end of the movie, Magda's boyfriend shoots Jonathan, the singer. When Jonathan falls backward into the water behind him, we can hear a splash. However, we do not see the water rise from where he falls in. Also, there are no ripples in the water.
The film features two troubadours several times throughout the film. Though we can hear the vocals and accompanying guitar and drum lines, this music almost never matches what the drummer and guitarist are actually doing with their instruments on screen. This was intentional on the part of the filmmakers and meant to be humorous. Their songs are a device used to narrate the story and the two men are not considered part of the in-universe cast of characters.
When Ted is at the chiropractor after helping the older man
move, the doctor says tenderness left of "L-7". There is no L-7. Parts of the vertebrae are labeled: C-1 to C-7, T-1 to T-12, and L-1 to L-5. However, the term "L7" is a slang term meaning "square", and this is most likely a subtle joke at the expense of Ted.
Tucker asks Pat if he designed the Estadio Olimpico in Santiago de Chile. Although there are six different soccer stadiums in Santiago, not a single one is called "Estadio Olimpico". Since Tucker was a fake, hadn't actually been to Chile, and sensed that Pat was a fake, he probably made it up to see what Pat's reaction would be.
After Ted is attacked by the dog in Mary's apartment and slides across the floor, he attempts to crawl away from the dog. We then see the dog bite Ted's ankle and the next shot is Ted's fingernails scratching the hardwood floor as the dog drags him back. If you pay close attention, Ted's fingers slide past the scratches made by the crew before the shot ends.