Denpa Onna to Seishun Otoko ep 04: What's with their shoes?

Could someone explain to me what these girls are doing with their feet? Repeated mistakes or usual Shaft weirdness?

08:49: Ryuuko is wearing shoes and socks:
11:09: Now she's wearing slippers and no socks:
12:36: She's wearing shoes and socks again:

But that's nothing compared to Maekawa:
11:20: She arrives, wearing shoes + socks:
11:37: Slippers, no socks:
12:57: Shoes + socks:
13:13: Shoes + socks (but she removed her costume):
13:52: Slippers, no socks:
14:00: Shoes + socks: