Also see:
Vote rigging: How to spot the tell-tale signs
https://www.bbc.com/news/world-africa-37243190
Too many voters
A high turnout in specific areas
Large numbers of invalid votes
More votes than ballot papers issued
Results that don't match
Delay in announcing results
Sounds oddly familiar to the problems and allegations with this election.
No, I don’t think it does sound familiar to a Gabon election.
Too many voters
"You never get a 98% or 99% turnout in an honest election. You just don’t.”
A high turnout in specific areas
"Why would one particular area, or one individual polling station, have a 90% turnout, while most other areas register less than 70%?”
Large numbers of invalid votes
"Keep an eye on the number of votes excluded as invalid. Even in countries with low literacy rates this isn't normally above 5%.”
More votes than ballot papers issued
Where ha that been verified?
Results that don't match
Where ha that been verified?
Delay in announcing results
"Finally something that is not necessarily a sign of rigging, but it is often assumed to be so."