In opening burial scene, Hasidim are saying Kaddish, the Aramaic prayer for the dead with the Sephardic pronunciation, which no Hasidim ever used.
At 25:10, when Mulder is getting up from the floor we can clearly see that his gun has no mag loaded, just an empty compartment for it.
Jacob Weiss is said to have belonged to Irgun ("Jewish Military Underground") and been arrested for terrorism by the British in 1959. However, the British pulled out of Israel when it became a recognized state in 1948, and Irgun was dissolved because there was now no motivation for it to exist. It would make no sense for an Israeli to have been arrested by the British in Israel in 1959. (Unless we are supposed to believe that he was carrying out terrorist acts in the UK and arrested there - but that is not suggested and would have little historical resonance in any case.)