The exterior of the home is shown as a ranch style, possibly a split-level, but clearly not enough height to accommodate a second storey. Yet interior shots show the main level as only a couple steps down from ground level and a full storey up from there, and even an attic up from there. The exterior and interior are severely inconsistent.
Mike Brady is shown to be an employee (not even a partner) in his architectural firm. That means unless he was paid substantial bonuses, his salary by 1970s standards would be far too low to support the costs of a live-in maid like Alice. This becomes even more apparent when the series makes it clear that Carol Brady does not work and thus Mike's income is the only thing supporting nine people, including himself.
Considering that Brady's have six children, including two already in adolescence when the series begins and Mike is an architect, no reason is given why they didn't purchase a much larger home. After all, they are apparently wealthy enough to employ a live-in maid, take expensive vacations and not to have Carol work.
The series attempts to tackle this later with Greg getting an attic room of his own. However, why this wasn't done in the first place is never explained; nor is why they don't on an addition or even consider a larger dwelling as time went by.
Each time the front of the Brady house is shown as though it were "evening", the same shot is used for "daytime". The evening shot of the house is only darkened. The same shadow that can be seen in the daytime shot in the lower right corner (caused by the roof) is seen on the evening shot.
The series never shows Alice having her own bathroom. The house clearly must have at least 3 full baths for the nine people who live there as it would be very difficult for Alice to use the children's upstairs bathroom and very unlikely that Brady parent would allow her to use their master bedroom one.
However, in the five year run of the program, Alice's bathroom is never shown although her rather tiny maid's quarters are several times.