diff --git a/internal/fakes/container.go b/internal/fakes/container.go
index ccda8d1c66..5042a1bb9a 100644
--- a/internal/fakes/container.go
+++ b/internal/fakes/container.go
@@ -128,9 +128,6 @@ func (b *fakeBackend) StartContainer(ctx context.Context, containerID string, op
 		ip := net.IP{192, 0, 2, byte(b.clientCounter)}
 		info.IP = ip.String()
 	}
-	if info.MAC == "" {
-		info.MAC = "00:80:41:ae:fd:7e"
-	}
 	info.Wait = func() {}
 	return &info, nil
 }
diff --git a/internal/libdocker/builder.go b/internal/libdocker/builder.go
index 135ce715c0..92707a09d4 100644
--- a/internal/libdocker/builder.go
+++ b/internal/libdocker/builder.go
@@ -156,9 +156,13 @@ func (b *Builder) archiveFS(ctx context.Context, out io.WriteCloser, fsys fs.FS)
 		return err
 	}
 
-	// TODO: errors
-	w.Flush()
-	w.Close()
+	// Handle tar writer errors properly
+	if err := w.Flush(); err != nil {
+		return err
+	}
+	if err := w.Close(); err != nil {
+		return err
+	}
 	return nil
 }
 
diff --git a/internal/libdocker/container.go b/internal/libdocker/container.go
index cc976e8499..4e1b62e8a4 100644
--- a/internal/libdocker/container.go
+++ b/internal/libdocker/container.go
@@ -156,7 +156,6 @@ func (b *ContainerBackend) StartContainer(ctx context.Context, containerID strin
 		return info, err
 	}
 	info.IP = container.NetworkSettings.IPAddress
-	info.MAC = container.NetworkSettings.MacAddress
 
 	// Set up the port check if requested.
 	hasStarted := make(chan struct{})
diff --git a/internal/libhive/api.go b/internal/libhive/api.go
index 62fecbb00e..84d4a5822c 100644
--- a/internal/libhive/api.go
+++ b/internal/libhive/api.go
@@ -321,11 +321,12 @@ func (api *simAPI) startClient(w http.ResponseWriter, r *http.Request) {
 // Note that jsonPath gets written to the result JSON and always uses '/' as the separator.
 // The filePath is passed to the docker backend and uses the platform separator.
 func (api *simAPI) clientLogFilePaths(clientName, containerID string) (jsonPath string, file string) {
-	// TODO: might be nice to put timestamp into the filename as well.
-	safeDir := strings.Replace(clientName, string(filepath.Separator), "_", -1)
-	jsonPath = path.Join(safeDir, fmt.Sprintf("client-%s.log", containerID))
+	ts := time.Now().UTC().Format("20060102T150405Z")  // yyyymmddThhmmssZ
+	safeDir := strings.ReplaceAll(clientName, string(filepath.Separator), "_")
+	fname := fmt.Sprintf("client-%s-%s.log", ts, containerID)
+	jsonPath = path.Join(safeDir, fname)
 	file = filepath.Join(api.env.LogDir, filepath.FromSlash(jsonPath))
-	return jsonPath, file
+	return
 }
 
 func (api *simAPI) checkClient(req *simapi.NodeConfig) (*ClientDefinition, error) {
diff --git a/internal/libhive/dockerface.go b/internal/libhive/dockerface.go
index 6c0aecc23f..b63a66208f 100644
--- a/internal/libhive/dockerface.go
+++ b/internal/libhive/dockerface.go
@@ -69,7 +69,6 @@ type ContainerOptions struct {
 type ContainerInfo struct {
 	ID      string // docker container ID
 	IP      string // IP address
-	MAC     string // MAC address. TODO: remove
 	LogFile string
 
 	// The wait function returns when the container is stopped.