Todd's shoes are different when he's riding toward Kurt Dussander's house from when he actually arrives.
At the end, the monitor shows a flat line and there's a solid tone, yet it still shows a bpm of 189 which then switches to and stays at 167.
When Brad Renfro (Todd Bowden) is bicycling to the home of Ian McKellen (Kurt Dussander), he is wearing sneakers and white socks. When Renfro arrives at McKellan's house, he is wearing white socks and black penny loafers.
After Dussander comes down the steps in the Nazi uniform, he approaches Todd and his hat switches hands between shots.
Dussander is wearing glasses in the hospital as he falls asleep and Kramer goes and looks him in the face. Later, as he wakes up to find Weiskopf speaking in German, Weiskopf hands him his glasses. He then suddenly discovers Kramer's absence so it was obviously the first time he'd woken up since falling asleep with them on.
Mr. French shows Todd a newspaper headline, part of which reads "...Camp Commandant Lead Double Life...". The correct spelling for the past-tense of "lead" is "led."
At the end of the movie as Dussender lays dead in the hospital bed his pupils are constricted when in fact they should be fully dilated if were dead.
Kurt Dussander, upon receiving his uniform given by Bowden, commented on how he received a "promotion". The new rank was that of a field officer; a Lieutenant Colonel (Americanized version; German version is Oberstleutnant
SS-Obersturmbannfuhrer). The SS insignia was always on the right collar, the other on the left. This occurs just after 30 minutes into the movie. About 52 minutes into the movie, the collar position of the insignia changes collars; the "SS" is now on the left collar, the other on the right. This mistake escapes many of us due to the fact we are seeing him looking at himself in a mirror, and so it seems to make sense. The truth is, of course, despite the use of a mirror, right is still right, and left is still left.
Some question Dussander's description of carbon monoxide gas being introduced to gas chambers through pipes, pointing out that Nazi extermination camps used Zyklon B pellets dropped through openings in the roofs of the chambers, which then released prussic acid (hydrogen cyanide) gas. While the extermination camps, Auschwitz I, Auschwitz II-Birkenau, Majdanek and KZ camp Sachsenhausen and Dacau did use the Zyklon B method, most of the other major extermination camps (Belzec, Sobibor, and Treblinka II) and KZ camps used large gas or diesel engines to produce carbon monoxide exhaust, which was then routed to the gas chambers through pipes. This was learned from the experiences of the T-4 project. (The Chelmno camp had no gas chambers, it instead used gas vans, in which the vans' own carbon monoxide exhaust was routed to the rebuild and airtight cargo bay of the vans, which held the victims.)
The SS uniform that Todd buys for Dussander has the collar insignia of an Obersturmbannführer (equivalent to Lieutenant Colonel). However the braided shoulder straps lack the single pips they should have for this rank.
FBI Special Agent Dan Richler's badge is the wrong design, the FBI badge is a shield with pointy bits and an eagle on top, his badge is an oval shield with no eagle.
A 3-point line is visible on the school's basketball court. The setting of the movie is 1984 and the 3-point line wasn't introduced to the high school game until 1987.
When Todd uses the basketball to kill the injured bird (implied but not shown), the sound it makes is the same thud of the ball hitting the wooden floor. The sound of the ball striking a bird would be different.
When Todd is walking down the hall to give Kurt Dussander the costume, the dolly track is visible on the floor in the hall.
When Mr. Dussander opens the box containing the Nazi costume, he comments that it is a very good recreation and reads that it is from a costume shop in "Tappan Zee, New Jersey". Tappan Zee is a body of water, not a town, though a famous bridge and area locations are named for it; they, like the actual town of Tappan, however, are just over the border in New York state.
Dussander is a major high-ranking Nazi war criminal, yet only one person recognizes him.
At the dinner scene the man points at a deer head on the wall and says, "that's a white tail buck". The deer head is in fact a mule deer and not a white tail deer.