Fortress Europe
The "Fortress Europe" set of rules is set between January and August 1944 and takes place on the European lines. The errata address a number of issues with the first release of the rule set. The specifications of all rocket launcher troops are set, as well as special rules for waging battle on an Italian front. Other additions include a fleshing out of the roles of several vehicles, including Jeeps and tractors, as well as a description of the value of an anti-tank rifle company.
Hammer and Sickle
The "Hammer and Sickle" rule set takes place between June and July 1944 on the Soviet front. The errata correct several mistakes with the original issue, including an entire specification table for a rocket mortar unit. They also adds the option of selecting armored transports instead of half-tracks as a bonus for gun platoons. The bunker bonuses and stats are given in detail as well.
River of Heroes
The "River of Heroes" rule set takes place in 1944 on the Vistula River in Poland. The errata for this set actually change the gameplay quite a bit, as they specify a few rules that were vague in the first release. Most notably, they state that only Udarny of the 8th Guard Rifle Corps from the "Stalin's Onslaught" scenario are allowed the "hardened veterans" special rule, rather than all riflemen. The errata further explain the added cost of Spetsnaz platoons by pointing out that in this rule set they are Pioneer SMG teams.
The errata also change a couple point values for armored cars and add a few armaments that were left out of both German and Soviet sides, such as the SU-57 hull-mounted gun for the Soviets and a couple of half-track units for the Germans.