Covalent atomic radii: oxygen vs nitrogen
The van der Waals radius of nitrogen is larger than that of oxygen, and has been calculated as such for quite a long time.
$$
\begin{array}{lll}
\hline
\text{Reference} &amp; R_\ce{O} &amp; R_\ce{N} \\
\hline
\text{Pauling, 1939} &amp; 1.40 &amp; 1.5 \\
\text{Bondi, 1964} &amp; 1.52 &amp; 1.55 \\
\text{Zefirov, 1974} &amp; 1.29 &amp; 1.50 \\
\text{Gavezzotti, 1983–1999} &amp; 1.40 &amp; 1.50 \\
\text{Batsanov, 1995} &amp; 1.51 &amp; \\
\text{Wieberg, 1995} &amp; 1.5 &amp; 1.6 \\
\text{Rowland, 1996} &amp; 1.58 &amp; 1.64 \\
\hline
\end{array}
$$
As is evident from the table, $R_\ce{N} &gt; R_\ce{O}.$ An interactive webpage of this reference can be seen here, which has the van der Waals radii of quite a few other elements as well.
Edit:
After OP mentioned the abnormality in Covalent Radii, I checked the radii in Concise Inorganic Chemistry, by J.D. Lee. The Covalent radius of Nitrogen $R_N = \pu{0.77 Å}$, whereas that of Oxygen is the same; $R_O = \pu{0.77 Å}$. Lee mentions that the radii are taken from Tom Moeller's Inorganic Chemistry book (which is from 1952)
OP should also be aware of the method used for calculating covalent radii: The Covalent Radius is defined as half the length of a single bond between two uncharged atoms. According to a more recent reference2 (which is used by Wikipedia), $R_N = \pu{73.4 pm}$ and $R_O = \pu{70.2 pm}$
Even more recent references, such as (3) use a different method of calculating covalent radius:

The covalent radius for nitrogen was obtained from N–N bond
distances in substituted hydrazines (only H or C atoms bonded to
N) with three-coordinated nitrogen atoms, excluding all structures
with an R factor larger than 10% or presenting disorder or
errors. The resulting value, $\pu{0.706(13) Å}$, is the average of 2200
crystallographically independent data and was used throughout
with three decimal figures for calculating other radii from N–
element bond distances to minimize rounding-off errors.
The covalent radius for $\ce{O}$ was derived from a
sample of 10,000 acyclic $\ce{C–O}$ bond distances, in a search limited to
purely organic compounds with two-coordinate oxygen and four-coordinate carbon atoms with R ≤ 5%, and the value obtained was $\pu{0.676(28) Å}$

A comparision of covalent radii has also been provided by the authors:
$$
\begin{array}{lll}
\hline
\text{Author} &amp; R_O\ (Å) &amp; R_N\ (Å) \\
\hline
\text{Cordero et al.} &amp; 0.706(13) &amp; 0.661(19) \\
\text{Alcock} &amp; 0.702 &amp; 0.659 \\
\text{Mingos} &amp; 0.74 &amp; 0.72 \\
\text{Butler and Harrod} &amp; 0.75 &amp; 0.73 \\
\text{Wells} &amp; 0.74 &amp; 0.74 \\
\hline
\end{array}
$$
References

Batsanov, S. S. Van Der Waals Radii of Elements. Inorganic Materials 2001, 37 (9), 871–885. DOI: 10.1023/A:1011625728803. (PDF)
Sanderson, R. T. “Electronegativity and Bond Energy.” Journal of the American Chemical Society, vol. 105, no. 8, Apr. 1983, pp. 2259–61.  doi:10.1021/ja00346a026.
Cordero, Beatriz, et al. “Covalent Radii Revisited.” Dalton Transactions, no. 21, 2008, p. 2832. doi:10.1039/b801115j.