When Matt is introduced to Alex at Bellucci's he takes off his jacket and in the next shot takes off his jacket again.
In Chicago, there is only a light dusting of snow, but at the cemetery, there are two or three feet of snow on the ground.
When Matt and Lisa are making love for the first time, Lisa takes off Matt's shirt and in the next shot Matt is wearing his shirt.
When Matt overhears Lisa on the telephone, she is arguing with Daniel; in the flashback to the same scene, she is talking to Alex.
Matt shakes three sleeping pills into his hand, but in the next shot, there is only one.
Matt is looking for Lisa at O'Hare Departures but runs into Rebecca, who should be at Arrivals (waiting for him)
There is never a vent between a restroom and another room - especially not in restaurant.
The rehearsal Luke attends is clearly a dress rehearsal -- it's the night before opening, the performers are in full make-up -- but there is no audience and the director interrupts to give notes.
There is never a vent between a restroom and another room -- especially not in restaurant.
Early in the movie, Matt overhears Lisa yelling at Daniel through the vent in the bathroom. But later, in Alex's flashback scene, we learn that the only reason Lisa was on the phone was because Alex had called her as a distraction. We hear that conversation in it's entirety but the flashback ends before Lisa leaves. After she talks with Alex, Lisa calls Daniel and cuts off their relationship. It's her conversation with Daniel that Matt overhears.
When Alex serves Mathew coffee in the champagne flutes, they both pick them up by the bowl instead of the stem which would be extremely hot to hold in their fingers.
When Alex serves Matthew coffee in the champagne glasses, she adds a cube of sugar but only stirs it for a second and the still-solid sugar cube is visible at the bottom of the glass while Matthew is drinking the coffee.
On the card that Luke gave Matthew, the number for Dragon Lady Shoes was 555 0123. However, when Lisa calls (and Matthew's in the shower) you can see the number on the painted windows of the shop, and it clearly states the number 555 0142 (or 555 0145). This is not the same as the card number.
When Matt tells Luke he has to go to a funeral, his mouth doesn't match what he's saying.
When Luke says to Alex, "Are we still going out tomorrow?" it is dubbed from, "Are we still going out tonight?" as his lips are mouthing the latter.
The morning of the second day, Luke pleads wretchedly with Matt to attend the play and meet Alex. In the event, Matt leaves at the curtain and Luke says nothing.