You can be caught about lying in an interview at any time after the fact. If I interviewed someone and found out they flat out lied in response to a question (side note: I don't ask about salary), it would be an instant no/suggestion to end a probationary period from me.
Because being stuck doing a job that's over your head every single day isn't fun, even if you're getting paid for it. When they say interviewing is a two-way street, they're right.
