Did Charlie actually have his guitar on the plane WITH him??? It was obvious that Sayid had taken Kate's place as a criminal being transported, but why would be he be being transported to Guam??
Charlie was upset because they made him check his guitar, which is why he thought he wouldn't find it. I think Charlie told Hurly to get on the flight, for sure, but not sure why he would want him to take a guitar. Seems like a minor original detail to fuss over.
I agree about Sayid, but the only thing I heard that made sense was that they were deporting him to Iraq and that Guam was a pit-stop on the way...