Concerning the "wise men" of Pharaoh:
According to Saadya Gaon in his commentary to the Torah he mentions (דבר הנעשה בחשאי ובהסתר) i.e. essentially slight of hand tricks. Also, mentioned in Emunoth and Deoth book 3 section 5 that they did things that were (כפא מסתורא אדא כשף) hidden to make...