When John and Jake do a drive-by at the steel mill in an attempt to start the gang war, several fires in barrels are burning. When they make their second pass, the smoke and fire can be seen going backwards, back into the barrels.
Not long after the driveby shoot-em-up at the abandoned steel mill, during the similar action at the basketball courts are interspersed 2 brief shots from the funeral driveby only 8 years earlier in Colors (1988).
During the drive-by attack on the Diablos, at least one shot is printed backwards--the flames are going into the garbage cans.
Camera crew shadow visible during the fight at the abandoned steel mill.