If some piece of information given by your ancestor in a record does not make sense, consider the possibility that he lied. People lied for many reasons, including
- wanting to get married
- wanting to enlist in the service
- wanting to avoid the service
- trying to escape their past (parents, spouse, children, debts, etc.)
An outright lie can be difficult to research around, but people did lie about their age, place of birth, name, marital status, etc.