General Relativity (bendy space causes gravity) is not the same as Special Relativity (moving frames of references). Only Einstein's Theory of Special Relativity has been demonstrated through experimentation (See the
Hadfel-Keatng Experiment).
No one has demonstrated that the fabric of space bends to cause the gravity we feel on earth, which is why General Relativity is rejected on this forum.
Like most physicists, Einstein has a lot of failed theories. He spent 40 years trying to unify electromagnitism and gravity, which didn't really get anywhere.
One other way he failed was in a 1935 paper called the "EPR Paradox" for Einstein-Podolski-Rosen, the authors. They tried to show that quantum mechanics could not be a complete description of reality with a careful argument. Unfortunately it did not convince everyone.
His most famous equation might be E = mc
2, but Einstein himself doubted how important it was. He dismissed the notion that it might one day be at the heart of a new energy source, declaring in 1934 that “there is not the slightest indication” that atomic energy will ever be possible.