What does “pick up in the current” mean?

I assume she's talking about how they don't think Tiffany could've gone far out to sea by being picked up in a current ( basically caught in a stream of seawater that is leading away from the shoreline). I believe these particular currents are called rip currents and they drag you from the shore if you get caught in it.

A current refers to a continuous stream of water. Think a river or stream. Ocean also have currents, where if you go far out, the water is continuously moving in global patterns. (see link below I don’t know how to post images lol). What she is saying is that if the girl swam out far enough, it would be likely that her clothing or body would have been caught in (picked up in) the current and brought back to shore. https://upload.wikimedia.org/wikipedia/commons/thumb/9/9b/Corrientes-oceanicas.png/800px-Corrientes-oceanicas.png

Its a slightly grammatically incorrect sentence, she should have said "I just didn't think that tiffany could've swam far enough out to be picked up in that current". It just means that the current caught tiffany and dragged her out to sea. The subtitles don't miss anything.