When Sarah and Trevor are in front of the radio station, you can see the frequency of the station is 84,9 FM. However, in the US we use a period as a decimal point, not a comma.
The M9 pistol Sarah uses when escaping from the hospital has a capacity of 15 bullets. It is fired 23 times without being reloaded before running out of ammo.
After leaving the hospital, Sarah and the others run over a large number of zombies, sometimes busting them into pieces. But when they stop, there is not a drop of blood anywhere on the vehicle.
The "Moron" zombie at the end of the movie has already been seen getting incinerated in the previous scene, in fact striking the same pose.
The bite wound on Bud's hand disappears while in the parking lot, then reappears when he is in the HMMWV.
Sarah uses a key to start up the HMMMV, but military HMMMVs don't need keys for ignition.
After receiving orders from Corporal Cross/Sara Bowman, Private Crane answers "Yes Ma'am". Only officers are referred to as "sir" or "ma'am" in the U.S. Army. The correct response should have been "yes, corporal"
Captain Rhodes wears matching Captain's bars on the lapels of his uniform. Army officers only wear rank insignia on their right lapel. The left lapel is reserved for that officer's branch insignia, i.e. crossed rifles for Infantry, crossed sabers for Cavalry, crossed pistols for Military Police, etc.
When they were riding in the HMMWV they picked up a local radio station on the SINCGARS. These do not pick up local radio stations.
When Sarah pulls up to her house, you see a license plate on the HMMWV. When in fact, military vehicles do not have plates. They are marked with a black star where the plates go.
Sara asks Trevor, "You loaded?" Trevor has a revolver and the cylinder is open as he spins the cylinder. The camera view is from the front of the revolver. Trevor responds to Sara, "Full up!" You can clearly see from the front of the revolver that the chambers are empty.
In the radio station right after Paul (Disc Jockey) turns into a Zombie and gets killed, Nina kneels down near a desk next to a computer. The computer is empty, it doesn't have any electronic components in the back like a video or network card. It's clearly a prop.
When Cpl Cross first arrives at the hospital with her mother there is a little boy being pushed in a wheelchair at the bottom left of the screen; despite being ill the actor is clearly smiling and looking straight at the camera.
Mena Suvari's character is referred to as "Cpl. Cross" in both conversation and on her uniform, but she is listed as "Sarah Bowman" in the credits.
Private Crain did not attack the other survivors after he turned into a zombie. The explanation given (by Sarah) is that the zombies retain some portion of their former selves, and that he was a vegetarian, thus not interested in them for their meat. If we accept this explanation, then following the same logic, while walking in the woods not long after, he should be trying to eat the available vegetation (trees, flowers etc). However, he does not. Therefore, there is either an error in that he didn't eat plants when he would have done, or a plot hole in why he wasn't eating the survivors.
At 6:47 zombie is seen being shot and falls to floor the disappears.
At the time of the film's release, the Army had already replaced its green camouflage Battle Dress Uniform with the pixel-gray Army Combat Uniform. Even if for some reason their unit hadn't gotten ACUs, the BDU is still worn improperly by every soldier in the film. They should have unit patches on the left shoulder, and an American flag on the right shoulder.
The gun that Sarah fires when escaping from the hospital clearly has no silencer, but the sound effect used each time it fires is one that a silenced pistol would make.
It is highly unlikely that a modest gun shop in a small town would have a significant stockpile of federally-regulated Class III automatic weapons for sale.
When Sarah enters the overcrowded local hospital with her mother, she asks a man to stand up so the mother can take the seat. In the next shot there are a lot of free seats on other benches nearby.
When Cross first visits her house, the shadows indicate it's no later than mid-afternoon. But Salazar had just stated that breakfast was in "like, 12 hours".