When Holly is in the kitchen pouring a glass of alcohol and is distracted by William, she pours most of it on the counter and only a small portion into the glass. However, when William enters the kitchen, the glass is full for a short period of time and then when they glance back at Holly it is almost empty again.
During the dinner with her mother, Holly is setting the table and when she reaches to put something on the table you can see her dress is torn at the armpit. Her sister then sits at the table and when she stretches again to hand her something, it is fixed.
In the opening argument scene, Gerry is wearing his suspenders over his shirt, you can see them when he takes off his jacket. He then takes off the suspenders and shirt and is wearing a singlet. Just before he catches Holly when she jumps on him, he is wearing the suspenders over his singlet. And then when they start kissing, the suspenders are gone again.
During the restaurant scene between Holly and Daniel, after Daniel leaves, the waitress picks up the extra service (flatware, plate, menu). The scene cuts and cuts back at a different angle and the waitress is seen picking up the plate and menu again.
During the scene when Holly is visiting her in-laws, Rosie is searching for a specific portion of the letter and turns the page from front to back. After Holly says/asks that Gerry knew she would come to visit them, Rosie once again turns the page from front to back.
During the scenes on the road, just prior to their first kiss, Holly is wearing Gerry's leather jacket which changes states of openness several times. At one point, the jacket is slightly open with the flaps flat against her chest, then the jacket is shown more open with the flaps flipped back on themselves, then switches back again. Then, Holly starts to walk away and remembers that she is wearing his jacket & reaches up to take it off. Cut to a long shot where it shows the jacket buttoned about halfway up from the bottom.
In the scene at the beginning when Gerry and Holly are fighting, Holly goes into the closet to put something away and Gerry puts his arms up in the doorway. Holly pushes his arm back to go into the bedroom and accidentally hits and moves the lampshade. Gerry looks at it and grabs it, but when they cut to a wider shot on the bedroom, the lampshade is perfectly straight again.
After Gerry gets smacked in the face by the "broken" suspender clasp, we see the silver clasp land under the dresser. Yet, when he's moaning and lifting his leg to get onto the bed, we can actually see the clasp still intact on the front suspender that came loose, which is dangling right behind him (just look between his legs). Of course, in the next shot, that clasp is gone.
When Holly and Daniel get into Yankee Stadium after hours, the batter's and baselines are perfectly drawn on the infield. These would not be present after hours. They are drawn with chalk and only put down after batting practice and just before the game. By game's end, they are worn away.