When the young Pink finds his father's service revolver and ammunition in his mother's bedroom, the ammunition has a metal jacket (i.e. the actual "bullet" part has a brass casing over it). When he dishes them out to his friends in the railway embankment the rounds are ordinary lead rounds without he brass casing.
As the jackbooted thugs march in a tunnel with Pink at the head, between the drug overdose and the fascist rally, they march left right left right. The visions cuts and the sound continues, left right left right. Cut back to the boots and now they are right left right left, one step out of time with the constant marching sound.
Several obvious mirror shots during the Fascist rally scenes: the crossing-hammer armbands switching arms, left-handed handshakes, the strap worn on Pink's shoulder when walking down the hallway switching shouders, the same neo-Nazi member appearing to be standing on both ends of the row of neo-Nazis while they are chanting "waiting" during the "Waiting for the Worms" sequence.