Capacitors can radiate acoustic energy when their plates move in response to electrostatic forces. Dielectrics may not behave in a perfect way, and their molecules might do weird things. Capacitors can even intercept electromagnetic energy from outside the capacitor body. Realistic capacitors exhibit non-ideal effects that can be modeled by augmenting the ideal model with parasitic.
Capacitors deviate from the classic capacitor equation in several ways. Some of these, such as current leakage and parasitic effects are linear or can be analyzed as nearly virtual components to the equivalent circuit of an ideal capacitor. The usual methods network analysis can be applied can be applied.