Even geniuses can err sometimes!
Einstein erred in thinking the universe should be static. In order to *force* his equations to allow this, he inserted the 'cosmological constant' into them.
It turns out that his equations with the cosmological constant are unstable, so even that solution didn't work.
Einstein was consistently against the conclusions of quantum mechanics. In order to show his issues, he proposed several thought experiments. many of these experiments have actually been done now. Einstein's intuition was uniformly wrong about quantum mechanics in these. The EPR paradox is only the most popular example of his errors.
A less well known example was in Einstein's theory of specific heats of metals. This was a quantum based (!) description of how much heat it takes to change the temperatures of metals. While his theory was better than the previous one (which assumed the specific heats to be constant), his predictions were consistently above the experimental realities. Debye eventually found the correct description for specific heats.
So, yes, even geniuses can be wrong. They are usually wrong for good reasons, but wrong none the less.