Character mistake: When Walter brings Cynthia's dog in the carrier to the bowling alley he refers to it as a Pomeranian while it is actually a terrier. Somewhat related, when the the Nihilists confront Dude in the bathtub, the dude refers to the ferret as a marmot. Walter later refers to the ferret as an amphibious rodent. Perhaps he was thinking of a mink.
Continuity mistake: In the opening scene when The Dude's head is repeatedly shoved in the toilet, almost all of the water is pushed out of the bowl and it's nearly empty. Soon the bowl is once again full, even though the toilet had not been flushed, which is the only way the bowl is normally refilled.
Chosen answer: There's no way of knowing. If the hiker was that far away, it could have been someone who happened to stray into the scene by accident. The filmmakers may or may not have noticed, but if they did, may have felt it added to the realism. I did this myself during the filming of a street scene for the TV show, "Northern Exposure." Filming was underway before I realised I was in the midst of it. I just kept walking like I was supposed to be there.
raywest