Truly I say to you, This generation shall not pass, till all these things be fulfilled - matt 24:34
to help explain this verse and determine the time frame one must read both sides of that verse to determine exactly who or what "THIS" means
the previous verses explain who this group is -
So likewise you, when you shall see all these things, know that it is near, even at the doors. - matt 24:33
so what "these things"? this is explained in verses 1-32 and further illustrated in the rest of the chaper which then folds into chapter 25
so - this prophecy is yet to be fulfilled and thus is not a false word. to understand a verse in the bible one must look for further references such as context and culture.