After 50 years of watching this film (probably more than 200 times), only a few months ago I noticed this for the first time: in the final showdown at Sad Hill, uco and Blondie meet eyes for a second, and Blondie gives a quick but perceptible nod. Has this been discussed before? I presume it was either inadvertent, or Blondie is sending a message that they're a team against The Bad.