When the man Thana meets in the bar holds her gun, he cocks it, but when he lifts it to his head, the hammer is no longer pulled back.
At c. 43 minutes, as Thana puts a pink bag in the trunk of an unsuspecting stranger's parked car, a light yellow car is parked closely in front. However, when the car is driven away immediately afterwards, the yellow car is several car-lengths away, leaving a sudden empty space.
When Thana pulls the gun on the man she met in the bar, she holds it close to his head, casting a shadow on his jacket. In the next shot, neither the gun nor the shadow can be seen. Returning to the longer shot, both are seen again.
When Thana shoots the Photographer, she fires her pistol 10 times. The most a .45 caliber automatic can hold is eight rounds--if you reload after firing 6. Yet she never reloads the gun even once.
The semi-automatic .45 caliber pistol Thana uses is actually a semi-automatic 9mm. It's a STAR model BM which is closely modeled after the original semi-automatic Colt .45 Caliber 1911, but was made in Spain and chambered in 9mm parabellum. You can even see it in the closeups of the gun; it says STAR on the slide.
When Thana pulls the dead burglar into the bathroom and rests him stomach-first over bathtub and steps away, the actor can be seen breathing with his back slightly moving up and down.
When Thana shoots the Photographer at his studio, it's clearly noticeable that "blood" is being thrown into the show from off-camera.
One band member is playing the trumpet, but a saxophone sound comes out of it. There is no trumpet sound in the song the band is playing.
Thana never appears to run out of bullets for her gun, and she frequently uses a full clip (around seven rounds) to kill her victims. Although Thana loads and re-loads a clip for her .45 caliber semi-automatic pistol, where she got all the ammunition is never explained.
There is no evidence to suggest that Thana has ever been shown how to handle an automatic pistol, let alone been trained how to fire one or achieved any proficiency; yet within two days of her being raped and acquiring the pistol, she is able to hit four men circling her, at night, each with a single shot, in rapid succession.