I make no claim to this in either its origin or veracity but upon first glance it looks plausible.
Actually, yes! Sort of.
There are no surface rivers on Earth that flow inland from the sea, although contrary to some answers here, such a river is merely extremely unlikely, not impossible.
In the tiny African country of Djibouti, across the Red Sea from Saudi Arabia, there is a little crater lake called Lake Assal. It lies 155m below sea level and is the saltiest lake anywhere in the world except Antarctica. It is, in fact, about ten times saltier than the ocean.
So how did Lake Assal become so salty? Simple: it is fed by seawater. It has no outflows. Water leaves it by evaporation only. And, not surprisingly, when you take salty water and evaporate water out of it, you get…saltier water.
Water from the Gulf of Tadjoura flows into deep underground aquifers, where it is heated by geothermal activity. This warm, salty seawater then flows out of hot springs near the lake, keeping it full despite the hot, arid climate that rapidly evaporates the lake's water. In short, unlike all sane lakes, Lake Assal was raised badly and never got the memo that water goes out of lakes and into the ocean.
Depending on your definition of “river,” you might call this aquifers-springs-lake system a system of rivers that flow from the sea towards (very low altitude) land.
Would it be possible for a similar water flow to exist on the surface and therefore be more recognizably a river? Yes, of course. The conditions that would make it possible are incredibly rare and complicated…but somewhere in the universe there is surely such a river.
You wouldn't be thinking of the tidal mangrove swamps would you?
