TV! (Top 5 signs of the Apocalypse Edition)
5) Peter is happy.
4) Earth-2!Olivia pretends to be shaky and "OMG-he-came-at-me-and-I-had-to-shoot-him-I-had-no-choice-OMG" in Peter's arms... and *nobody* notices how rather uncharacteristic this is.
3) You unearth parts of universe-destroying machines... and you feel that's a good thing.
2) Astrid is beginning to channel her inner Walter.
And the Number 1 sign of the Apocalypse is... Walter Bishop thinks your line of research is too dangerous. Walter Bishop.