Among the disappearing items are player characters, guns, hands, and even horses. The bug seems to be isolated to the multiplayer game, but take a look at the invisible horse bug in action:
When the game launched last night, many users also reported problems with logging into multiplayer.
A Rockstar representative told Kotaku "if you're having issues please email RDRSupportteam@rockstargames.com. We are also actively on the forums helping people with any questions they may have about the game. Thank you all for your support and we look forward to getting a fix out as quickly as soon as we can."