When Klondike goes to get cigarettes, he tells Vega he's going get Camels. When he comes out the liquor store, the pack in his hand is Pall Malls.
When sitting in bed watching TV, Vega changes the channel. The TV, however, still displays the same channel (3) on the display.
In the beginning of movie, Bad Ass is sitting in the back of the bus, and a lady in a purple dress walks on and takes a seat to the right of the bus, sitting in the seat closest to the aisle. When the skin-head insults the black man, the lady has been replaced by man and is no longer visible.
When Frank first crashes his bus, the front headlights on left side are demolished. In the next scene they are ok, and functioning again.
The buses being used during the bus chase keep changing. The bus Vega is driving with San Diego listed as the destination has the numbers 1106 in some scenes on the front, and in others it has no numbers or place to show numbers. Meanwhile, Panther is driving the bus bound for Las Vegas, and the 1106 numbers intermittently appear and disappear on the front of his bus.
At 8:08 you can see 5 service stripes (Hash marks) on Frank's uniform, which would signify 15 years continuous service in the US Army. Frank served 7 years of which 6 years were in Vietnam. 2 service stripes would be proper.
No wonder he was rejected by the police. The coat of arms on their response was that of Nigeria. He applied to the wrong country.
When Bad Ass cop friend picks him up in the police cars Bad Ass is carrying a large bag of groceries. A few blocks later he tells him to pull over and let him out. He had no large bag of groceries and they were not in the front seat. As he got in the front seat, Bad Ass had put the groceries in the back seat. When he got out of the car, emotions between the two men were running high, so that both of them could conceivably have forgotten about the grocery bad.
When the garage explodes as Frank is running out, he doesn't get blown forward by the blast.
All the passenger transport buses and police car have the same license plate number.
When Klondike is shot, you see what looks like a paint-ball mark, bright red. The view of him on the ground shows a more blood like maroon color.
When Frank shoots the basketball after breaking up a basketball game, the players act like he makes the shot but it's actually an air ball and the net doesn't move.
When the convenience store is getting robbed, one of the reaction shots of the clerk is flipped as noted by all the text on the bottles in the background being mirrored.
The transit bus Frank always gets on and off is always number 114. No other buses in the city?
When Frank is holding Renaldo outside the window, you see a cop car coming down the street towards them. Yet, no cop shows up to stop Frank.
A stuntman for Panther is clearly visible several times during fight scenes with Frank.
As Frank successfully makes a basketball from afar into the hoop, the wide shot clearly shows Danny Trejo's stunt double who isn't all that well covered up by the hat and has a much skinnier chin and shorter beard.