I was wondering if at the end the watch would return to Smith.
And by "return" I mean to his possession.
The important wasn't the "adventure" of the watch, right? It was to show that Smith already recovered what he had discarded with the watch back then. The watch doesn't matter.
@Catsuey
It was the he got separated with Talas.
He had presented the watch but her mother in law had give him back. When he gave up on Talas he abandoned the watch in the desert.