When Jamie and Bobby are having sex in the kitchen Jamie's shoe falls off and then appears back on moments later.
When Traci is having sex in the men's room with Robert, he is shown removing his shirt at one moment; with his tan lines accentuating his bare bottom. However, during the rest of the seen, Robert's jeans are shown to still be buckled on.
It's not explained if Michael was already cheating on Jamie, with his assistant. Or if she was hitting on him all the time and Michael had gotten into the habit of rebuffing her, to the point he couldn't have sex with Jamie without it triggering him.
Plus if he was cheating already, there's no explanation as to why. Jamie was MORE than willing to have sex with him. Unless he was drugged into sex with the woman via trickery and he felt too ashamed.
Traci is vocally against sex until the pill pulls out her repressed lust, so she very likely wasn't on birth control. So there's a good chance she got pregnant from having sex with Robert in the restroom. Plus the fact the two are together after the time skip implies it did indeed happen; so Robert is taking responsibility.
When Sarah magically puts her clothes on, she says her underwear is on backwards. However, she only put her shirt and jeans on; not change what she was already wearing underneath.