Goofs

On the Bridge scene under the graveyard, Tom Manning is thrown and slides under the door just before it closes. However Hellboy also slides under later in the scene when the door should have already been closed.

During his first fight with Sammael, Hellboy fires six shots from his gun. He only loaded four bullets before the fight. He subsequently fires at least another three, without ever reloading.

When Hellboy is under the train, he keeps getting smacked on the lower edges of his horn stumps. When he stands up, it's the upper edges that are glowing red hot from the impacts.

In the library, when Hellboy was walking into the crime scene, there were only three glass display cases in the center of the room, but when the monster threw Hellboy through the cases, Hellboy crashed into four cases before hitting the window

When Liz is lying on the ceremonial table, she's apparently wearing nothing under the cloth. After Hellboy and Myers bring her into the hallway, she has a shirt.

When Agent Myers was at the gates of the Bureau for Paranormal Research and Defense, he had a retina scan. The machine scanned his right eye, but it identified it as his left eye.

The shadow of the Earth on the Moon is the same diameter for the eclipse. The Earth's shadow is much larger and would inscribe an arc on the moon aside from the Lunar eclipse taking hours instead of minutes.

At one point, Manning stops Hellboy from using his gasoline lighter to relight his cigar, explaining it is better to use a wooden match to preserve the flavor. While he has a point, it is moot when relighting a cigar that had previously gone out or been extinguished because that will taste horribly no matter what is used to relight it.

In many fight scenes, characters are hit hard enough that they fly through the air. They fly in a straight line, when they should follow a parabolic arc.

The Caprice taxi that Liz and Myer are riding in has its rear windows rolled all the way down. This is not possible for those model years of Caprices as the way the door is shaped prevents the windows from going all the way down.

Hellboy is fireproof. He isn't affected by fire in any of the scenes in the whole movie. Yet after Hellboy emerges from under the train in scene nine, he touches his stunted horns which are now scalding hot and reacts in pain.

There is a huge difference between being supernaturally fireproof due to his genetics and not being able to feel pain.

Abe has webbed fingers, yet in all the scenes where he is wearing gloves he looks like he has normal hands. Since he's wearing gloves. And gloves are made for human hands.

His webs are flexible and can contract enough to fit into gloves.

Rasputin died in 1916, and was not alive in WWII.

As Professor Broom explains later in the movie's universe, the public's perceptions of "known facts" of historical figures - such as Hitler being dead in 1945 is wrong, he was actually died much later 1958 in the Occult Wars. The same lack of information by the public happens to Rasputin. We see him alive in 1944.

When Ilsa offers the gold to the Russian general in the freight container with the Tunguska artifact, she presents the suitcase with one hand. This amount of gold would be too heavy to be lifted with one hand - at least for a woman of her stature. However, Ilsa is a supernatural or has been enhanced by supernatural forces, as evidenced by the fact she still looks as young as during World War II, 50 years earlier. She also has supernatural strength. Later in the film, she is seen swinging a big sledge hammer one-handed with ease.

When Liz burns out the nest of Samael she is shown surrounded by blue flames. a blue flame would indicate that the fire is at least 1800 Kelvin, but the cave is unaffected, all rocks melt at temperatures above ~1500 Kelvin. However, just because the flame temperature is 1800 Kelvin does not mean it immediately heats up the rock to melting temperature. It needs to transfer sufficient energy to do that. And that means there needs to be a lot more energy transferred than to merely heat up the rock. The flame also needs to provide the additional enthalpy of fusion to overcome the molecular bonds and transform the solid rock into a liquid.

Flipped shot: In the underground tunnels next to the subway, Hellboy's big arm, which should be his right, is on his left side.

Underground, just after Abe is injured underwater, and the two agents are killed, Hellboy is walking into a room. As he enters, his RIGHT hand is normal and holding his gun. Just after he approaches the table, now, his LEFT hand is normal and holding the gun. His large hand has changed sides.

Whenever anyone fires an automatic pistol in the film, as when Myers shoots Sammael in the alley, there is no rearward action of the slide, no ejected shell casings or apparent recoil, and the muzzle flash is obviously superimposed, because the shooter is not illuminated by it. The only exception is agent Clay's gun when he is shooting at Kroenen, which in fact is a blank-firing weapon - the gun even locks empty (slide back).

When Kroenen is fighting off the guards during the museum scene, as he moves his arms around, the knife and sheath on his upper arm bends and twists significantly, revealing that the prop is made of rubber and fiber-glass.

Railing appears and disappears on the stone bridge (which also alters), as it's used for CGI destruction.

When Hellboy stops the car by slamming his hand into the bonnet and flips the car, the grille and bumper are seen to break off the front and as it flips over the grille about to fall on Hellboy, but when the car lands the grille and bumper are nowhere to be seen.

They were obviously thrown clear by the impact and landed out-of-shot.

When Hellboy jumps from one roof to another for the second time while eavesdropping on Liz and John, he misses the edge of the roof. An instant later however, his left hand can be seen coming up first and grabbing the ledge, then the right one. So what did he hang onto in the first place? The window seen in the following reverse wide shot is too low in the wall to be of any use.

He wasn't hanging on to it. He was jumping up from it.

Liz closing and opening her mouth while Hellboy carries her, though she is dead.

As was revealed later in the movie, she was only semi-dead, since she came back alive.

In the picture of the WWII Army unit at the beginning of the movie, there are 2 black soldiers present. However, American Armed Forces units were not integrated until 1948, three years after WWII.

After Red throws Manning under the closing door and the causeway begins to crumble under his feet, Hellboy is obviously being suspended on a trapeze since the bricks under his feet are dropping and he is staying elevated and flailing about as opposed to falling or moving forward. You can see when the camera goes to a behind the back shot, that the collar on his coat is perked up, indicating that there is a cable supporting him which was digitally erased in post-production.

When fighting Sammael in the subway, Hellboy is thrown into a raised window. Briefly, before smashing through the window, the wire holding him can be seen.

Just after the opening credits we see what is later revealed to be Ilsa, Kroenen and a guide in a snowy, rocky setting which is described as "Birgau Pass, Moldavia" in the caption - Birgau, or Borgo (a popular location in vampire lore), is in fact in Romania. Moldavia is the ancient region now known as Romania.

Although Abraham Lincoln was shot on April 14 1865, he actually died in the early morning of April 15 1865.

When we're first introduced to Liz it is clearly Halloween. Another woman points out the window behind Liz and says there's a big red man down there. In response the doctor says Santa doesn't come for another month.