  A strong outburst of the X-ray transient V404 Cygni (= GS2023-338) was
observed in 2015 June/July up to a level of 50 Crab in the hard X-ray domain.
At this level of photon flux, an instrument's behavior may be severely tested
and some instrumental artifacts could affect the data analysis. We are
interested in the SPI instrument aboard the INTEGRAL mission and have performed
thorough checks to ensure a correct handling of the data. By analyzing the
observations throughout the outburst, we have observed that the high energy
domain (above 500 keV) sometimes exhibits unexpected features which are worth
careful examination. Spurious triggers are known to affect the MeV region and
we suspected that this phenomenon could be accentuated by the huge photon flux.
We have investigated this issue, specifically during high flux periods and
actually found that artificial high energy bumps may appear with the current
standard analysis procedure. However, if the specific selection events usually
used in the 650-2200 keV energy is applied down to 450 keV, the spurious noise
and the associated spectral features are removed. We present how to obtain
reliable spectral results on the high energy emission of V404 Cyg at extreme
flux levels and demonstrate that with the correct configuration, the hard X-ray
emission, up to a few MeV, is modeled by a two component model as observed in
Cyg X-1 and for V404 Cygni itself at lower flux levels.
