Before Twitter and before that, Facebook, all we usually had for sources were bloggers who wrote about what they had seen or interacted as to TAR. Posts were also made to various forums that could be found using search engines. Infrequently there were be media reports often in languages other than English.
This is where we had the raw material to assemble spoilers once it was possible to track Race filming in real time. In addition, use was also made of techniques and sources that were developed in the early seasons to reconstruct the actual legs after broadcast of episodes in early seasons.
Don't become totally dependent on Twitter and Facebook and Instangram. They're just tools and not the end all and be all of Race tracking.