When Manikkam (Rajni) is tied to a pole and hit repeatedly, blood stains on his white vest appear, disappear and change between shots.
When Rajni is fighting a goon who is carrying a sword and sparks appear when the sword strikes against a metal grill frame, the electric wire used to generate the sparks is clearly visible at the base of the sword in multiple shots.
One of the promises that Manikam makes to his dying father is to get a Medical College seat for his younger sister without letting anyone know about Manikam's secret identity. However Manikkam does reveal his secret identity to the college principal to scare him so that he gives a seat to Manikkam's sister. Hence when Manikkam says "Dad, I have fulfilled your dying wishes", it is not true.