Other mistake: Poirot saves his entire company except his captain - that's what it was stated, although it's unclear how that can be the case since the explosion was massive and left Poirot disfigured and had several other companions close. That's besides the point though, which is; the captain walked into a trip-wire across the bridge, but earlier shots showed the Germans (several of which were waiting on the same side the Belgians come from) retreating in haste, running exactly where the captain walked. The trap would work only if the Germans were waiting on the other side of the river. There was no chance for them to arm the trap during their hasty escape.
Other mistake: In the origin story of Poirot's facial hair, we see the damage on his cheek is massive, well into the cheekbone. His girlfriend says he'll grow a moustache to cover it, and surprisingly, it works - nevermind the fact that scar tissue wouldn't grow hair. When we see the scar without the moustache, while smaller than the initial damage, it still extends into the cheek at the level of the nostrils in a way that the 'stache couldn't seamlessly cover like in the rest of the movie and its prequel.
