Irony of love
Nicholas decides that he wants to marry Alizon when his brother Humphrey is betrothed to her. However, when Humphrey changes his mind about Alizon, so does Nicholas, showing the superficiality in his love.
Irony of witchcraft
The major of the town accuses an innocent, wealthy young woman of being a witch, and performing certain evil activities, such as turning a man into a dog. However, we discover that the major only accuses the woman as he has his eye on her property and wealth, which will be given to the city once she dies. As such, throughout this play, we see the irony of witch accusations, and how they were never based on factual information.
Irony of Skipps
Throughout the play, the mayor accuses Jennet of having turned Skipps into a dog, using her powers as a witch. She is nearly killed for these crimes, but at the end of the play Skipps is found in human form, so the case is dropped.