Blackthorn, this is the text that refers to the incident.
http://www.biblegateway.com/passage/?search=lu ke%2024:13-24:35&version=50
The idea that he was in disguise is feasible. After all, he had been arrested and crucified by the Romans on a charge of sedition, and he had 'died' incredibly quickly; his 'corpse' had been taken away by friends rather than being left for the vultures, and had subsequently disappeared from a guarded tomb. I can't help feeling that this story is based in politics, and there's a lot more to it than meets the eye. Maybe he had to 'keep his head down'.
Your mention of Erich von Daniken surprises me. Are you a fan? I am - but there aren't many of us around here. I hadn't realised he'd written about this.
Weecalf, it's possible, but the texts seem to suggest that he wasn't recognisable physically.