This looks like the kind of homework question where the "correct" answer actually depends on the person who will be grading it. It may depend on what was taught earlier in the course; there are some things that could be overlooked unless you were specifically told "don't do it like that" the previous day.
One actual problem is that the router's eth1 and eth2 interfaces use the "all-zeros" aka "network" address of their respective subnets, which is typically considered to be reserved in a similar way to the 'broadcast' address. (Many decades ago, the all-zeros address used to be the subnet broadcast address. Now it no longer is – the all-ones address is used for broadcast – but all-zeros remains reserved all the same.)
This may or may not also apply to the router's eth0 as well. It's unclear what the netmask of eth0 is – the address 192.168.13.0 would be a reserved "network address" if the subnet was /24 or smaller, but a perfectly valid host address in /23 or larger. (Of course, this is in addition to the problem of eth0 overlapping with eth2, which you already mentioned.)
- Host A4's IP address 192.168.10.39 is outside subnet A.
- Host A5's IP address 192.168.10.40 is subnet A's broadcast address.
These are the wrong way around – .39 is the broadcast address (the last address within the subnet) which means the next address .40 is outside the subnet.
The switch's MAC address in subnet B is incorrect because H is not a hexadecimal number.
That's true, but I'd question whether it is even relevant to a diagram that focuses on IP configuration – switches are "transparent" at MAC layer; their MAC address is only used for protocols that switches themselves participate in (such as STP or LACP) but is never used in frames going through that switch (frames sent by a host would directly reference another local host or gateway as their destination MAC). Indeed an umanaged switch that doesn't speak STP/LACP/LLDP would usually not even have a MAC address at all.
So perhaps the real mistake is that the switches have their MAC addresses indicated in the first place (…or that other devices don't).
Where are the remaining two mistakes? I though maybe subnet B has way too many host IP addresses, but that's not really a mistake.
Using a /23 is not a technical mistake in itself. It may be overkill or wasteful from the network designer's perspective, but is completely legal within the protocol.
