diff --git a/gtsam/geometry/Unit3.cpp b/gtsam/geometry/Unit3.cpp
index ad6a41bde..3a07b8b98 100644
--- a/gtsam/geometry/Unit3.cpp
+++ b/gtsam/geometry/Unit3.cpp
@@ -101,6 +101,7 @@ Matrix Unit3::skew() const {
 
 /* ************************************************************************* */
 Vector Unit3::error(const Unit3& q, boost::optional<Matrix&> H) const {
+  // 2D error is equal to B'*q, as B is 3x2 matrix and q is 3x1
   Matrix Bt = basis().transpose();
   Vector xi = Bt * q.p_.vector();
   if (H)
diff --git a/gtsam/navigation/AttitudeFactor.h b/gtsam/navigation/AttitudeFactor.h
index 64603bd99..8d301db72 100644
--- a/gtsam/navigation/AttitudeFactor.h
+++ b/gtsam/navigation/AttitudeFactor.h
@@ -46,7 +46,7 @@ public:
   /**
    * @brief Constructor
    * @param nZ measured direction in navigation frame
-   * @param bRef reference direction in body frame (default Z-axis)
+   * @param bRef reference direction in body frame (default Z-axis in NED frame, i.e., [0; 0; 1])
    */
   AttitudeFactor(const Unit3& nZ, const Unit3& bRef = Unit3(0, 0, 1)) :
       nZ_(nZ), bRef_(bRef) {
diff --git a/gtsam/slam/lago.cpp b/gtsam/slam/lago.cpp
index abb72021a..1f5d0f2df 100644
--- a/gtsam/slam/lago.cpp
+++ b/gtsam/slam/lago.cpp
@@ -223,7 +223,7 @@ static PredecessorMap<Key> findOdometricPath(
     const NonlinearFactorGraph& pose2Graph) {
 
   PredecessorMap<Key> tree;
-  Key minKey;
+  Key minKey = keyAnchor; // this initialization does not matter
   bool minUnassigned = true;
 
   BOOST_FOREACH(const boost::shared_ptr<NonlinearFactor>& factor, pose2Graph) {
diff --git a/gtsam/slam/tests/testLago.cpp b/gtsam/slam/tests/testLago.cpp
index 5e4b2faf2..0d586a051 100644
--- a/gtsam/slam/tests/testLago.cpp
+++ b/gtsam/slam/tests/testLago.cpp
@@ -10,7 +10,7 @@
  * -------------------------------------------------------------------------- */
 
 /**
- *  @file  testPlanarSLAMExample_lago.cpp
+ *  @file  testLago.cpp
  *  @brief Unit tests for planar SLAM example using the initialization technique
  *  LAGO (Linear Approximation for Graph Optimization)
  *