The dramatic irony that takes place at the end of Scene 1 is that we know that Antigone has buried Polynices, but Creon, the Chorus, and the Guard do not.
Antigone buried Polynieces as she wanted that the family should do the burial rights after the death. Creon didn't want Polynices' body to go through the privilege of burial because he considered Polynices as a traitor. This is very well known to the audience that it is Antigone who has buried Polynieces but the other characters are unknown of this. Such type of ironical conditions is known as dramatic irony.