When Agent 86 confronts Krochanska just before being gassed, he is clearly looking straight ahead and pointing his gun at someone of adult human size. It is later established that Krochanska is a dog, meaning Agent 85 must have been threatening a blank wall, well over the dog's head.
When Demetrios radios Krochanska before gassing Agent 86, he gives several sentences of exposition that the attacker - a dog - couldn't possibly understand.
Max & 99 are saved from the toxic gas by their hide-away gas masks. However, Agent 44 would have still been hiding in the compartment wall, and would not have had any warning about the gas.
At the end, when pouring wine, Smart calls it a Beaujolais, but the bottle is a claret bottle.
Demetrios says the gas will render a human unconscious in 30 seconds but Max isn't affected by the gas until 54 seconds after the gas starts (and the Conductor doesn't become affected at all).