At least they did not call the episode Invasion that would be misleading.
I felt the trailers gave it away that The Flash would be the start of the crossover.

Supergirl is a fantastic show. So if course they should include her!!!!

False Advertising is illegal. THat does not apply to a trailer here.
Someone else pointed out that it was well known online for weeks in advance that Barry and Cisco was going to only be on for a few moments.
That also nullifes False Advertisement laws.
Also, trailers are not beholden to false advertisement laws ever. That would bankrupt the economy and stifle creation when everyone can be sued for not including everything in a trailer, or removing scenes from the movie.
I am a man with Asperger's Syndrome, so please forgive me if my posting seems weird.

I agree. False advertising.

Pathetic. As someone else pointed out they shouldn't have even bothered to include Supergirl in the crossover.
That 1 minute cameo at the end
does not
count.