Identifying indicators of a possible chemical weapons incident can include all EXCEPT:

In the context of identifying indicators of a possible chemical weapons incident, "High flying clouds" is not typically considered a relevant indicator. Observing anomalous cloud formations at high altitudes does not provide a clear or direct connection to chemical weapon usage.

In contrast, the other options represent more concrete signs that could suggest a chemical incident. For instance, a lack of insect life can indicate potential contamination of an environment, as certain chemicals can be harmful to insects, disrupting local ecosystems. Unusual liquids may be indicative of leaked or spilled chemicals, which is a clear sign of a chemical hazard. Similarly, unexplained odors can be a strong indicator of toxic agents, especially if they differ from normal environmental smells. Therefore, while the other indicators are more directly related to the assessment of chemical threats, high flying clouds do not have the same level of significance in this context.