When Snowbird arrives at the demolished cabin, supposedly seconds after hearing the explosion, the timbers are already blackened and smoldering, which would only happen after hours of combustion.
When the Kaznian minister of defense contacts Lex about Snowbird, he comments "She is a copy of Supergirl. Her memory is absent." When the same scene is replayed a few minutes later, the line "Her memory is absent" is missing, and the question "Can you come right away?" has been added.
Snowbird, like Supergirl, has her ears pierced. Also like Supergirl, her skin is invulnerable, so how could anything pierce them? As a lucky opportunity of chance, they were pierced by Lex the night Mercy Graves used his dispersal device to seed the atmosphere with kryptonite, as seen at the end of "Fallout (2018)".