Martha and Sophie's wounds from the cat attack vanish by the next day...
In the supermarket scene the items on the shelves are moved from Martha walking past to when Francis walks past.
After the goon takes Martha inside the house from the pouring rain, her hair and clothes go from soaked to mostly dry.
Martha falls rear first into a puddle of blood. She even remarks on it: "I've got blood in my ass crack!" However, right after, her pants are dry and clean. No sign of blood on her behind.
When Francis and Martha are walking by the pool, you can see the red nose on him. In the next shot, he does not have it on and puts it on his nose again.
When Hopper is pointing his revolver at Francis at the end, the cylinder is empty - no bullets are visible. Perhaps this is why Francis is so confident that Hopper won't shoot him.
After the closing shootout, it is raining heavily, but the sky in the background is clear blue and the trees and church across the street have sunlight on them. When Francis and Martha descend the stairs, they also have sunlight on them. Thus, the rain is revealed as fake.
Around 86 minutes, Steve (RZA) shoots Reynolds/Hopper (Tim Roth). Francis asks Steve if he has any gummy bears left, and Steve replies "I saved you a couple"; then he tosses them to him. Francis gives one to Martha. When she puts it into her mouth, you can clearly see it's red. Earlier, Francis told Steve he liked the green ones (not red). This is clearly an error.
Bruce pulls the pin on a hand grenade and then panics. Francis helps him put the pin back in. Bruce is still shaken up, so Francis helps him sit down and says "Breathe in through your mouth and out through your nose." Francis is doing this himself (simultaneously) to show him; and if you watch closely while this is occurs, Bruce is doing it: Breathing in through his mouth and out through his nose, even though this is wrong.
In the parking lot knife fight the knife makes metal clinging sounds when pulled from a pair of pants, and even when just being waved around in the air.
In the scene when Martha and Francis are walking by the pool, Martha puts her sunglasses on top of her head. When she looks down to sip from her drink, you can clearly see what looks like the stand up lights around them.