Actually, you can have a lot of fun with harmless loonies. The PCs are already expecting to walk around a corner and find three witches hissing at them about doom and goats and whatnot; an occasional red herring is amusing. For example: A pale little girl in a raggedly dress, sitting gravely by the side of the road, who watches the PCs approach in silence, and says, "Tey'res marnsther's down 'at way." The PCs may question her, but eventually they'll turn their backs on her-- which is when she vanishes. Guaranteed to slow down their march...
A large hunting dog, obviously the property of a noble, that runs up to a PC, whining, and refuses to leave his side, casting fearful glances all about. When the party stops to rest, the dog vanishes.
At a crossroads: a foot-high cross with a crucified rat.
A man in a chef's uniform running down the road gibbering "The knuckles... the horrible knuckles..."