The 2 macguffin
that everyone is after, and which are very important to the plot, are the briefcase and the watch.
According to the script, the briefcase contains diamonds. But Tarantino thought it was too similar to the plot of "Mad Dogs" and left the ambiguity. So we're not shown what's in the briefcase in the end.
A watch that spent many years in various arseholes and contracted dysentery in a Vietnamese camp is a memento macguffin because it's important as a memory.