I've been skimming over this trying to find if a landlord can demand rent for me staying a day over my 30 day notice. Specifically because the landlord is out of town that day. Can a landlord demand full rent for me being one day over my 30 day notice because he is out of town to do a walk through? Seems illegal.
Assuming you have a lease of a year which expires on the 24th, you are supposed to surrender the premise by the end of that day. If you don't, then you are engaging in "unlawful detainer", and the landlord could go ahead with the legal process of booting you out. Supposing that in the meantime you do surrender the premise, then per §1952.3, then it becomes an ordinary civil action. Either way, the landlord would be entitled to some relief (there is no law saying that you can stay an extra day). According to the Department of Real Estate (p. 17), the court can award owed-rent damages to the landlord up to the date of the judgment. It's hard to say when that judgment would be handed down, because it depends on how busy the courts are, plus if the matter goes from (high-priority) unlawful detainer to (low-priority) regular civil procedure, that would extend the time to judgment and potentially the size of your liability. Typically, when you become a holdover tenant then you are in the "month-to-month" realm, so your rent obligation would extend for another month (by default, an agreement is assumed to be for a month).
However: it's generally easy to get out of an apartment by the deadline and hand over the keys to the landlord or his agent. A "walk-thorough" can be scheduled for the next Monday (for example), though you might want to take pictures before you go. There is actually no legal requirement that the landlord allow you to be present for the post-move-out inspection, so in the worst case, you might have to get into a separate legal squabble over the security deposit, if you think he is making up damage.