When the father is waiting up for Nicole, he sees her walking towards the house. He runs to the couch to pretend he was already asleep. When he kicks off his shoes, one lands on the floor by the couch while the other appears to bounce off the table onto the floor on the far side of the table. We see Nicole walk in. Then when we see the father again, the straps of one of his shoes can be seen on the table by the ashtray.
When Nicole gets up from the pool lounger, the other guests display their shock at her thong swimsuit. But they had been sitting there for quite some time. So some of them at least would have seen what she was wearing when she first went to the poolside.