Not all exhibitions will be closed on 4th June. You can go to Skład Długa where you can find exhibitions from ShowOFF Section or see Indrė Šerpytytė's project "1944-1991" in the Museum of Contemporary Art in Kraków.
Apart from that, while walking by the Vistula, it's worth finding the outdoor exhibition by Sophie Ristelhueber: Every One (1994) - ul. Podgórska 16. And of course please don't forget about the exhibitions from Krakow Photo Fringe -> KPF program