The appearance didn't start to well according to a press report, in part because of the rain but because "Director Michael Bay and the two leads Megan Fox and Shia LaBeouf were more than two hours tardy for a special screening of “Transformers: Revenge of the Fallen.”" This led to a press walkout the next day when they where late again for a press conference. Thanks to Katie for the link.
Right now the cast is in Rome, Italy for that country's premiere but don't when that is event occurs. After that they will head to Spain.
Update:Michael Bay commented on the press walkout.
We had too much scheduled that day and traveled from another country. We are so sorry for this. We then got stuck in crazy traffic and yes we were late to the premiere. The entrance to the cinema had 600 Korean fans standing in the rain for two hours. These fans were among the greatest I have ever experienced.