Near the beginning when they are being chased by the hand, the car makes a wide turn and the drivers side window is down, then in the next shot a hand member jumps on the car and the window is up.
Ray Schoonover was wounded in combat and lost his hand, which meets the criteria for a Purple Heart, yet when in uniform, his ribbon rack does not include the award. The first ribbon in the top row is crimson indicating a Legion of Merit award.
When the officer leads Frank into the cell block, another officer opens the door with a key, and yet there is also the buzzing sound of the door being opened remotely.
In a US court, an "expert witness" must be explained to be so: credentials given and examined, standing questioned through voir dire by the opposing counsel, and the status of "expert" agreed upon by both sides.
During Frank Castle's trial, in the back of the courtroom hangs a 48-star US Flag rather than the current 5-star flag.
Matt is missing from the trial, which is occurring during the day, because he is back at his apartment due to Elektra's injury. Yet the light coming in from the apartment windows indicates it is still night and the windows are lit up by streetlights.