How we cite our quotes:
Nurse: [Medea] hates her sons […] I dread to think of what is hatching in her mind. (1)
Euripides doesn't shy away from some pretty obvious foreshadowing here. Medea's path of revenge is pretty clear even from the opening moments of the play. Of course, the Athenian audience the play was written for would've already know the Medea myth quite well.
Medea: Oh, what misery! […] Cursed sons, and a mother for cursing! Death take you all – you and your father […]
Nurse: Why make the sons share in their father's guilt? (20-21)
The Nurse points out the irrationality of Medea's rage. This lady is so out of control that she plots to annihilate all products of she and Jason's union. The boys' innocence is no defense against the irate Medea
Medea: [Creon] lets me stay one extra day, to make three enemies corpses:
ha! father, daughter, and my husband. (57)
There's an incongruity here. Medea does end up killing Creon and his daughter, but doesn't make any attempt to kill Jason. Also, she makes no mention here that she plans to kill her sons. It's unclear if she just changes her mind somewhere along the way, or if she's lying about her exact plans. Of course, it could also be sloppy plot-making on the part of Euripides.