Patzer

Stu's wedding ring disappears and reappears between shots in the scenes leading up to his big speech.

The baseball bat disappears and reappears several times from the street in front of the phone booth.

During the first couple of scenes inside the booth, the sticker on the receiver is worn out and barely readable. After the first close-up the worn out section of the sticker is replaced with a new part, boasting clearly the name of the phone company.

When Stu is walking outside Mario's restaurant, his cigarette appears and disappears between shots.

The angle of the sniper's rifle scope constantly keeps changing. It keeps going from left to right back and forth every few minutes. It would have been impossible for him to go from one building to the next in that short amount of time.

Captain Ramey has a New York City Police Department Detective's badge (wrong rank).

The caller's intent to frame Stu for the murder of the pimp is flawed in several ways. Firstly, Stu would have had no gunshot residue on his hand. Second, hollow-point bullets do not fragment on impact, but flatten out to achieve a larger wound, so there would've been a bullet left behind. Third, when investigating deaths by gunshots, the investigator fires comparison bullets to help match the bullet found in the victim or the wound caused by the bullet. Fourth, the entrance wound would show that the pimp was shot from behind, but when he was struggling with Stu they were face to face, meaning Stu couldn't have possibly shot him in the back from that position.

At the end of the film, the police just let anyone walk around the crime scene: in addition to the caller you also see various tourists gathered around the phone booth. The police would never ever do this: as Leon the pimp was murdered right by the phone booth it is a crime scene and as such must be cordoned off for the forensics team to arrive, instead of letting people contaminate the crime scene. Even though the police "know" the pizza guy did it, they still need to look for forensic evidence.

The caller tells Stu that channels 2 and 5 were coming to see him; this would be correct since channel 2 is the CBS affiliate for New York city, and channel 5 is the FOX affiliate But the news vans that show up indicate that channels 5 and 8 are covering the story. The nearest broadcast channel 8 is in Connecticut. The only channel 8 in the New York City area is used by a cable station for a premium channel or local programming.

The hookers freak out after thinking Stu shot the pimp, which is odd as Stu had been assaulted by a larger man with a baseball bat. Even if Stu had been the shooter it is odd they would be surprised someone defended themselves.

When the caller/sniper gets a bit twitchy, threatening to shoot Stu's wife and the police officers, we hear him cocking the rifle five separate times. At no point do we hear him un-cocking the rifle between those moments, but he would have to physically cock and load the rifle every time he needs to fire a round. But since there are two rifles in play (one left with the dead pizza guy, and one the Caller carries in the final scene), the Caller could easily have had an empty rifle that he cocked, seeing how he uses the sound to intimidate Stu.

In the beginning, the narrator states that the phone booth is scheduled for demolition by Verizon. However, the booth has a Bell Atlantic sign on its top, which is a different corporation.

The caller contradicts himself by correcting Stu that he never kids when Stu says, "You gotta be kidding," about the caller calling one of his significant others and then later saying, "I'm kidding; I had a very happy childhood."

When Sergeant Cole tells Captain Ramey they need a warrant to find out if Stu is in fact talking with his psychiatrist, Ramey refuses because he doesn't want to risk Stu's life on a technicality, it's not a technicality, it's the law.

No red dot laser designed for targeting would be visible in daylight at the distance shown, especially on a dark surface such as the black suit jacket worn by Stu. The red dot seen in the film is a crude optical effect.

When the camera pans on Stu coming around a corner to the phone booth, extras (especially one with a box) can be seen standing very still and not moving. Only when Stu comes around the corner do they start moving.

When the 911 operator hangs up on Stu's cell phone call, there's a dial tone from his cell phone, but cell phones don't emit dial tones. (This is a common error in film and TV.)

When Stu moves his face in one of the close-ups you can see an ear piece in his left ear.

When Leon is trying to get Stu out from the phone booth near the start of the movie, the camera pans around from a low angle, the camera operator is reflected in the glass of the booth.

Although the film is set in New York, it was filmed in LA. When we see news reporters arriving, there is a shot of a female reporter in the bottom left of the screen. An LA public transport bus can be seen passing by in the background.

The "robot guy" is credited as Nigerian but when Stu pays for the broken doll, he speaks Swahili, mostly spoken in East Africa.

At the end of the movie as Stu (Colin Farrell) lies in the ambulance after being shot, he is given medication for the pain which makes him very disoriented just in time for The Caller (Kiefer Sutherland) to show up and taunt him. The person who administered the medication just hops out of the ambulance. Any time an injured person would be given such a strong medicine, they would be monitored to ensure that they have no negative reaction.

Stu's reason for using a phone booth to speak to Pamela doesn't quite hold up; his wife may check his cell phone logs, but it's perfectly legitimate for a publicist to be speaking regularly with a client.

At the end of the film, the caller walks to the crime scene with the rifle case without raising any suspicion.

Right after Stu is shot and the police find the dead pizza guy, Stu's wife runs over and embraces/kisses Stu. Moments later while she is still embracing him, the dead pizza guy is wheeled over on a gurney. No way they would have gotten a gurney up, loaded him on and brought him down that fast. Not to mention moving a dead body from a crime scene without any forensics or investigators doing their thing first.

When Stu's wife is with the police trying to talk Stu out of the phone both she tries to say "Do what they tell you to do, Stu!". Instead what she actually said was "Stu what they tell you do!". (When putting on the subtitles for the movie it confirms she was supposed to say "Do what they tell you to do, Stu!".)

Early in the film when the Stu swears at the pizza delivery man, Colin Farrell tries not to laugh.