I don't know which marathon it was, but it was not posted at CSR nor the bus stops. Their management agreed they dropped the ball because there were many of us affected. We were waiting for a bus at about 7:45AM. AK and DHS buses came and went like crazy. After a long time and a call to the main desk, a bus for Epcot came at 8:30AM. Off we went with about 25 people on the bus. Then the backup and wait. We were told they cannot go to Epcot and we have to go to TTC then take the monorail. At 9:30, we get to the TTC only to get into monorail lines that went everywhere. It was so crazy, CMs were suggesting to get to DHS or AK by bus at TTC. We do and get to DHS just before 11AM. We were given 3 FPs each when we got there. When we got back to CSR, there was a message from the manager at the front desk (no details). We expected the Mousekeeper broke something and they wanted to talk to us. Nope. The manager called us down to apologize for the issue. She stated that they should have notified guests the night before and should have had signs up at the bus stops. She gave us 3 FPs for our entire party for the next day as well.
Things may have changed since then, but I make it a point to know if there is a marathon. If there is, no Epcot or MK that day.