  An oriented $k$-uniform hypergraph is said to have Property O if for every
linear order of the vertex set, there is some edge oriented consistently with
the linear order. Recently Duffus, Kay and R\"{o}dl investigated the minimum
number $f(k)$ of edges in a $k$-uniform hypergaph with Property O. They proved
that $k! \leq f(k) \leq (k^2 \ln k) k!$, where the upper bound holds for $k$
sufficiently large. In this short note we improve their upper bound by a factor
of $k \ln k$, showing that $f(k) \le \left(\lfloor \frac{k}{2} \rfloor +1
\right) k! - \lfloor \frac{k}{2} \rfloor (k-1)!$ for every $k\geq 3$. We also
show that their lower bound is not tight. Furthermore, Duffus, Kay and R\"{o}dl
also studied the minimum number $n(k)$ of vertices in a $k$-uniform hypergaph
with Property O. For $k=3$ they showed $n(3) \in \{6,7,8,9\}$, and asked for
the precise value of $n(3)$. Here we show $n(3)=6$.
