Hi,
The strange scene for me came immediately following the blowing up of the bridge. Remember how Tuco lands in the bunker with his "tail in the air?" Well, his tail is still up there the following day! What's more, is that the entire armies, both Union and Southern, move out sometime during the night and all that racket caused by the mobility of two great forces does not wake either Tuco nor Blondie. Moreover, none of the Union soldiers woke up their new fellow compatriots to let them know it was time to move on! Very strange to me, how they were left behind and unnoticed, being new recruits and all.