Other: At the end of the opening credits, you can see Angel's reflection in the puddle on the floor. Since he is a vampire, this should not happen.

Character mistake: The slogan of Angel Investigations changes several times. In some episodes, it's "We help the helpless," while in others it's "We help the hopeless."

Other: In the last scene of the episode, Angel kicks the guy out of the glass building. This guy's a vampire, and you can see his reflection in the glass windows. Vampires aren't supposed to have reflections.

Continuity: When Angel kicks the vampire out the window, he does it with little effort and movement, but when the shot goes from outside the building, he's swinging his body like he's put more into it.

Other: In the scene when Angel runs after the barman towards the end, after the barman has tried to pass on the demon to Kate and Angel stopped him, there is a mirror, and when Angel runs past it, he has a reflection.

Continuity: In the season one episode 'I Will Remember You' when Buffy and Angel are talking in the sewer Buffy's hair goes from being just a few strands over her shoulder to having a whole side over it, and back again.

Revealing: When Angel stands at the cabinet with a file folder in his hand, you don't see the folder in the reflection in the window (which Cordelia uses as mirror to put on her lipstick) but you can see the cabinet.

Continuity: When Cordelia is putting on lipstick she uses the windows as mirror. In the reflection we see the top drawer of the cabinet is open the whole time, but it is later opened by Angel.

Revealing: In the scene where Kate finds her father dead, just after the shot of his neck wounds, she is sitting over him and you can see the father blinking a few times.

Factual error: According to the show, Angel learned quite a few languages when he was evil. However, when he tries to start a conversation with a red-faced demon, he makes terrible mistakes. He said "Hablo Espanol?" which literally means "Do I speak Spanish?" and he said something like "Are you from Byelorussia?" in a tongue that hardly resembled Russian, although according to the captions, it was said in Russian.

Continuity: In the final fight, Angel gets stabbed on his right side. In the slow-motion bit before his opponent chooses not to fight any more, the wound switches to his left for one shot.

Continuity: When Faith is sitting at the window and looks at the piece of broken glass she used to torture Wesley, it has a different shape than the one she first takes to torture Wesley. When she drops it out the window it has its original shape again.

Revealing: When the insect creature is crawling on the ceiling its hair doesn't falls down towards the floor, it "falls" towards the ceiling.

Revealing: When Alonna is kidnapped, there is a vampire on the left side of the screen who is not wearing any mask over his face, though sunlight is falling on him.

Plot hole: When a pack of vampires kidnap Gunn's sister Alonna, they use smoke bombs and gas masks. Since vampires don't breathe like humans do, they wouldn't need the gas masks.

Continuity: In Season One Finale, "To Shanshu in LA" when Wes is lecturing Cordy on wants and desires, the number of bites taken from the doughnut changes, in one instance it breaks in half, most visibly when Wes takes a bite from Cordy's doughnut on the angle change.

Other: In "To Shanshu in LA" in season one, as Angel is pulling out of parking lot to follow the W&H Trucks, you can see his reflection in his rear view mirror (vampires have no reflections). Also odd that throughout the first season the rear view mirror is removed in some episodes.

Continuity: In the season one finale "To Shanshu in LA," near the end Angel is fighting Vocah in the mausoleum and Angel rips off Vocah's mask, revealing the maggoty face underneath. In subsequent shots of Angel from behind Vocah, you can still see the edges of the mask on his face.

Continuity: When Wesley is explaining that Angel feels like he doesn't belong in the world, the amount of donut he's holding changes.

Visible crew/equipment: At the end of the episode where Wesley is studying the Shanshu scroll in Cordillia's apartment, the boom mike appears at the top of the frame TWICE.