It is true that he did not think the land, labor, capital triad was useful for value and price theory, and thus he, unlike Rothbard (the ownership of land and labor played distinct roles from the ownership of capital goods in Rothbard’s production theory, whereas Mises, as far as I know, never really elucidated his production theory), downplayed the importance of the land/labor (original factors of production) vs. capital good (produced factor of production) distinction, especially as less important than the higher-order vs. lower-order and producer’s vs. consumers’ good distinction…
The modern theory of value and prices is not based on the classification of the factors of production as land, capital, and labor. Its fundamental distinction is between goods of higher and of lower orders, between producers’ goods and consumers’ goods. When it distinguishes within the class of factors of production the original (nature-given) factors from the produced factors of production (the intermediary products) and furthermore within the class of original factors the nonhuman (external) factors from the human factors (labor), it does not break up the uniformity of its reasoning concerning the determination of the prices of the factors of production.
and that he warned that, if misinterpreted, the definition of “capital good” as “produced factor of production” can possibly result in confusion regarding “real capital”…
Capital goods have been defined also as produced factors of production and as such have been opposed to the nature given or original factors of production, i. e., natural resources (land) and human labor. This terminology must be used with great caution as it can be easily misinterpreted and lead to the erroneous concept of real capital criticized below. (…)
We may acquiesce in the terminological usage of calling the produced factors of production capital goods. But this does not render the concept of real capital any more meaningful.
But, of course, no harm can result if, following the customary terminology, one occasionally adopts for the sake of simplicity the terms “capital accumulation” (or “supply of capital,” “capital shortage,” etc.) for the terms “accumulation of capital goods,” “supply of capital goods,” etc.
But when he did use “capital good” as a term, he either went ahead and used the “produced factor of production” definition that excludes original factors of production (labor and land)…
I. As a result of the providential care of our forebears we have at our disposal an ample stock of intermediate products (capital goods or produced factors of production) and of consumers’ goods.
II. The intermediary products or capital goods, the produced factors of further production, change hands in the course of events; they pass from one plant to another until finally the consumers’ goods reach those who use and enjoy them.
or, he used a more sophisticated definition, which still clearly excluded labor. This is his more refined definition of capital good…
"At the outset of every step forward on the road to a more plentiful existence is saving–the provisionment of products that makes it possible to prolong the average period of time elapsing between the beginning of the production process and its turning out of a product ready for use and consumption. The products accumulated for this purpose are either intermediary stages in the technological process, i.e. tools and half-finished products, or goods ready for consumption that make it possible for man to substitute, without suffering want during the waiting period, a more time-absorbing process for another absorbing a shorter time. These goods are called capital goods. "
And this is how he defines labor…
“The employment of the physiological functions and manifestations of human life as a means is called labor.”
“The employment of physiological functions and manifestations of human life” is not a “product” one can “accumulate” for the purpose of prolonging the period of production.